tor-browser

Element.h (98342B)

---

/* -*- 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/. */

/*
* Base class for all element classes; this provides an implementation
* of DOM Core's Element, implements nsIContent, provides
* utility methods for subclasses, and so forth.
*/

#ifndef mozilla_dom_Element_h__
#define mozilla_dom_Element_h__

#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <utility>

#include "AttrArray.h"
#include "ErrorList.h"
#include "Units.h"
#include "js/RootingAPI.h"
#include "mozilla/AlreadyAddRefed.h"
#include "mozilla/Assertions.h"
#include "mozilla/Attributes.h"
#include "mozilla/BasicEvents.h"
#include "mozilla/CORSMode.h"
#include "mozilla/FlushType.h"
#include "mozilla/Maybe.h"
#include "mozilla/PseudoStyleType.h"
#include "mozilla/RefPtr.h"
#include "mozilla/Result.h"
#include "mozilla/RustCell.h"
#include "mozilla/UniquePtr.h"
#include "mozilla/dom/BorrowedAttrInfo.h"
#include "mozilla/dom/DOMString.h"
#include "mozilla/dom/DOMTokenListSupportedTokens.h"
#include "mozilla/dom/DirectionalityUtils.h"
#include "mozilla/dom/FragmentOrElement.h"
#include "mozilla/dom/NameSpaceConstants.h"
#include "mozilla/dom/NodeInfo.h"
#include "mozilla/dom/RustTypes.h"
#include "mozilla/dom/ShadowRootBinding.h"
#include "nsAtom.h"
#include "nsAttrValue.h"
#include "nsAttrValueInlines.h"
#include "nsCaseTreatment.h"
#include "nsChangeHint.h"
#include "nsDebug.h"
#include "nsError.h"
#include "nsGkAtoms.h"
#include "nsHashKeys.h"
#include "nsIContent.h"
#include "nsID.h"
#include "nsINode.h"
#include "nsLiteralString.h"
#include "nsRect.h"
#include "nsString.h"
#include "nsStringFlags.h"
#include "nsTHashMap.h"
#include "nsTLiteralString.h"
#include "nscore.h"

class JSObject;
class mozAutoDocUpdate;
class nsAttrName;
class nsAttrValueOrString;
class nsContentList;
class nsDOMAttributeMap;
class nsDOMCSSAttributeDeclaration;
class nsDOMStringMap;
class nsDOMTokenList;
class nsFocusManager;
class nsGenericHTMLElement;
class nsGenericHTMLFormControlElementWithState;
class nsGlobalWindowInner;
class nsGlobalWindowOuter;
class nsImageLoadingContent;
class nsIAutoCompletePopup;
class nsIBrowser;
class nsIDOMXULButtonElement;
class nsIDOMXULContainerElement;
class nsIDOMXULContainerItemElement;
class nsIDOMXULControlElement;
class nsIDOMXULMenuListElement;
class nsIDOMXULMultiSelectControlElement;
class nsIDOMXULRadioGroupElement;
class nsIDOMXULRelatedElement;
class nsIDOMXULSelectControlElement;
class nsIDOMXULSelectControlItemElement;
class nsIFrame;
class nsIHTMLCollection;
class nsIPrincipal;
class nsIScreen;
class nsIURI;
class nsObjectLoadingContent;
class nsPresContext;
class nsWindowSizes;
struct JSContext;
struct ServoNodeData;
template <class E>
class nsTArray;
template <class T>
class nsGetterAddRefs;

namespace mozilla {
class DeclarationBlock;
class MappedDeclarationsBuilder;
class EditorBase;
class ErrorResult;
class OOMReporter;
class ScrollContainerFrame;
class SMILAttr;
struct MutationClosureData;
class TextEditor;
namespace css {
struct URLValue;
}  // namespace css
namespace dom {
struct CheckVisibilityOptions;
struct CustomElementData;
struct SetHTMLUnsafeOptions;
struct SetHTMLOptions;
struct GetHTMLOptions;
struct GetAnimationsOptions;
struct ScrollIntoViewOptions;
struct ScrollToOptions;
struct FocusOptions;
struct ShadowRootInit;
struct ScrollOptions;
class Attr;
class BooleanOrScrollIntoViewOptions;
class Document;
class HTMLFormElement;
class DOMIntersectionObserver;
class DOMMatrixReadOnly;
class Element;
class ElementOrCSSPseudoElement;
class PopoverData;
class Promise;
class Sanitizer;
class ShadowRoot;
class StylePropertyMapReadOnly;
class TrustedHTMLOrString;
class UnrestrictedDoubleOrKeyframeAnimationOptions;
template <typename T>
class Optional;
enum class CallerType : uint32_t;
enum class ReferrerPolicy : uint8_t;
enum class FetchPriority : uint8_t;
enum class PopoverAttributeState : uint8_t;
}  // namespace dom
}  // namespace mozilla

using nsMapRuleToAttributesFunc = void (*)(mozilla::MappedDeclarationsBuilder&);

// Declared here because of include hell.
extern "C" bool Servo_Element_IsDisplayContents(const mozilla::dom::Element*);

already_AddRefed<nsContentList> NS_GetContentList(nsINode* aRootNode,
                                                 int32_t aMatchNameSpaceId,
                                                 const nsAString& aTagname);

#define ELEMENT_FLAG_BIT(n_) \
 NODE_FLAG_BIT(NODE_TYPE_SPECIFIC_BITS_OFFSET + (n_))

// Element-specific flags
enum : uint32_t {
 // Whether this node has dirty descendants for Servo's style system.
 ELEMENT_HAS_DIRTY_DESCENDANTS_FOR_SERVO = ELEMENT_FLAG_BIT(0),
 // Whether this node has dirty descendants for animation-only restyle for
 // Servo's style system.
 ELEMENT_HAS_ANIMATION_ONLY_DIRTY_DESCENDANTS_FOR_SERVO = ELEMENT_FLAG_BIT(1),

 // Whether the element has been snapshotted due to attribute or state changes
 // by the Servo restyle manager.
 ELEMENT_HAS_SNAPSHOT = ELEMENT_FLAG_BIT(2),

 // Whether the element has already handled its relevant snapshot.
 //
 // Used by the servo restyle process in order to accurately track whether the
 // style of an element is up-to-date, even during the same restyle process.
 ELEMENT_HANDLED_SNAPSHOT = ELEMENT_FLAG_BIT(3),

 // If this flag is set on an element, that means that it is a HTML datalist
 // element or has a HTML datalist element ancestor.
 ELEMENT_IS_DATALIST_OR_HAS_DATALIST_ANCESTOR = ELEMENT_FLAG_BIT(4),

 // If this flag is set on an element, that means this element
 // has been considered by our LargestContentfulPaint algorithm and
 // it's not going to be considered again.
 ELEMENT_PROCESSED_BY_LCP_FOR_TEXT = ELEMENT_FLAG_BIT(5),

 // If this flag is set on an element, this means the HTML parser encountered
 // a duplicate attribute error:
 // https://html.spec.whatwg.org/multipage/parsing.html#parse-error-duplicate-attribute
 // This flag is used for detecting dangling markup attacks in the CSP
 // algorithm https://w3c.github.io/webappsec-csp/#is-element-nonceable.
 ELEMENT_PARSER_HAD_DUPLICATE_ATTR_ERROR = ELEMENT_FLAG_BIT(6),

 // If this flag is set, this element is in
 // Document::mContentIdentifiersForLCP.
 ELEMENT_IN_CONTENT_IDENTIFIER_FOR_LCP = ELEMENT_FLAG_BIT(7),

 // Remaining bits are for subclasses
 ELEMENT_TYPE_SPECIFIC_BITS_OFFSET = NODE_TYPE_SPECIFIC_BITS_OFFSET + 8
};

#undef ELEMENT_FLAG_BIT

// Make sure we have space for our bits
ASSERT_NODE_FLAGS_SPACE(ELEMENT_TYPE_SPECIFIC_BITS_OFFSET);

namespace mozilla {
enum class PseudoStyleType : uint8_t;
class EventChainPostVisitor;
class EventChainPreVisitor;
class EventChainVisitor;
class EventListenerManager;
class EventStateManager;

enum class ContentEditableState {
 Inherit,
 False,
 True,
 PlainTextOnly,
};

namespace dom {

struct CustomElementDefinition;
class Animation;
class CustomElementRegistry;
class Link;
class DOMRect;
class DOMRectList;
class Flex;
class Grid;
class OwningTrustedHTMLOrNullIsEmptyString;
class TrustedHTML;
class TrustedHTMLOrNullIsEmptyString;
class TrustedHTMLOrTrustedScriptOrTrustedScriptURLOrString;

// IID for the dom::Element interface
#define NS_ELEMENT_IID \
 {0xc67ed254, 0xfd3b, 0x4b10, {0x96, 0xa2, 0xc5, 0x8b, 0x7b, 0x64, 0x97, 0xd1}}

#define REFLECT_NULLABLE_DOMSTRING_ATTR(method, attr)            \
 void Get##method(nsAString& aValue) const {                    \
   const nsAttrValue* val = mAttrs.GetAttr(nsGkAtoms::attr);    \
   if (!val) {                                                  \
     SetDOMStringToNull(aValue);                                \
     return;                                                    \
   }                                                            \
   val->ToString(aValue);                                       \
 }                                                              \
 void Set##method(const nsAString& aValue, ErrorResult& aRv) {  \
   SetOrRemoveNullableStringAttr(nsGkAtoms::attr, aValue, aRv); \
 }

#define REFLECT_NULLABLE_ELEMENT_ATTR(method, attr)      \
 Element* Get##method() const {                         \
   return GetAttrAssociatedElement(nsGkAtoms::attr);    \
 }                                                      \
                                                        \
 void Set##method(Element* aElement) {                  \
   ExplicitlySetAttrElement(nsGkAtoms::attr, aElement); \
 }

#define REFLECT_NULLABLE_ELEMENTS_ATTR(method, attr)                        \
 void Get##method(bool* aUseCachedValue,                                   \
                  Nullable<nsTArray<RefPtr<Element>>>& aElements) {        \
   GetAttrAssociatedElements(nsGkAtoms::attr, aUseCachedValue, aElements); \
 }                                                                         \
                                                                           \
 void Set##method(                                                         \
     const Nullable<Sequence<OwningNonNull<Element>>>& aElements) {        \
   ExplicitlySetAttrElements(nsGkAtoms::attr, aElements);                  \
 }

class Element : public FragmentOrElement {
public:
#ifdef MOZILLA_INTERNAL_API
 explicit Element(already_AddRefed<mozilla::dom::NodeInfo>&& aNodeInfo)
     : FragmentOrElement(std::move(aNodeInfo)),
       mState(ElementState::READONLY | ElementState::DEFINED |
              ElementState::LTR) {
   MOZ_ASSERT(mNodeInfo->NodeType() == ELEMENT_NODE,
              "Bad NodeType in aNodeInfo");
   SetIsElement();
 }

 ~Element() {
   NS_ASSERTION(!HasServoData(), "expected ServoData to be cleared earlier");
 }

#endif  // MOZILLA_INTERNAL_API

 NS_INLINE_DECL_STATIC_IID(NS_ELEMENT_IID)

 NS_DECL_ADDSIZEOFEXCLUDINGTHIS

 NS_IMPL_FROMNODE_HELPER(Element, IsElement())

 NS_IMETHOD QueryInterface(REFNSIID aIID, void** aInstancePtr) override;

 /**
  * Method to get the full state of this element. See dom/base/rust/lib.rs for
  * the possible bits that could be set here.
  */
 ElementState State() const { return mState; }

 /**
  * Returns the current disabled state of the element.
  */
 bool IsDisabled() const { return State().HasState(ElementState::DISABLED); }
 bool IsReadOnly() const { return State().HasState(ElementState::READONLY); }
 bool IsDisabledOrReadOnly() const {
   return State().HasAtLeastOneOfStates(ElementState::DISABLED |
                                        ElementState::READONLY);
 }

 /**
  * Return true if this element has contenteditable="plaintext-only".
  */
 [[nodiscard]] inline bool IsContentEditablePlainTextOnly() const;

 virtual int32_t TabIndexDefault() { return -1; }

 /**
  * Get tabIndex of this element. If not found, return TabIndexDefault.
  */
 int32_t TabIndex();

 /**
  * Get the parsed value of tabindex attribute.
  */
 Maybe<int32_t> GetTabIndexAttrValue();

 /**
  * Set tabIndex value to this element.
  */
 void SetTabIndex(int32_t aTabIndex, mozilla::ErrorResult& aError);

 /**
  * Sets the ShadowRoot binding for this element. The contents of the
  * binding is rendered in place of this node's children.
  *
  * @param aShadowRoot The ShadowRoot to be bound to this element.
  */
 void SetShadowRoot(ShadowRoot* aShadowRoot);

 void SetLastRememberedBSize(float aBSize);
 void SetLastRememberedISize(float aISize);
 void RemoveLastRememberedBSize();
 void RemoveLastRememberedISize();

 /**
  * Make focus on this element.
  */
 // TODO: Convert Focus() to MOZ_CAN_RUN_SCRIPT and get rid of the
 //       kungFuDeathGrip in it.
 MOZ_CAN_RUN_SCRIPT_BOUNDARY virtual void Focus(const FocusOptions& aOptions,
                                                const CallerType aCallerType,
                                                ErrorResult& aError);

 /**
  * Show blur and clear focus.
  */
 MOZ_CAN_RUN_SCRIPT_BOUNDARY virtual void Blur(mozilla::ErrorResult& aError);

 /**
  * The style state of this element. This is the real state of the element
  * with any style locks applied for pseudo-class inspecting.
  */
 ElementState StyleState() const {
   if (!HasLockedStyleStates()) {
     return mState;
   }
   return StyleStateFromLocks();
 }

 /**
  * StyleStateLocks is used to specify which event states should be locked,
  * and whether they should be locked to on or off.
  */
 struct StyleStateLocks {
   // mLocks tracks which event states should be locked.
   ElementState mLocks;
   // mValues tracks if the locked state should be on or off.
   ElementState mValues;
 };

 /**
  * The style state locks applied to this element.
  */
 StyleStateLocks LockedStyleStates() const;

 /**
  * Add a style state lock on this element.
  * aEnabled is the value to lock the given state bits to.
  */
 void LockStyleStates(ElementState aStates, bool aEnabled);

 /**
  * Remove a style state lock on this element.
  */
 void UnlockStyleStates(ElementState aStates);

 /**
  * Clear all style state locks on this element.
  */
 void ClearStyleStateLocks();

 /**
  * Accessors for the state of our dir attribute.
  */
 bool HasDirAuto() const {
   return State().HasState(ElementState::HAS_DIR_ATTR_LIKE_AUTO);
 }

 /**
  * Elements with dir="rtl" or dir="ltr".
  */
 bool HasFixedDir() const {
   return State().HasAtLeastOneOfStates(ElementState::HAS_DIR_ATTR_LTR |
                                        ElementState::HAS_DIR_ATTR_RTL);
 }

 /**
  * Get the inline style declaration, if any, for this element.
  */
 DeclarationBlock* GetInlineStyleDeclaration() const;

 /**
  * Get the mapped attributes, if any, for this element.
  */
 StyleLockedDeclarationBlock* GetMappedAttributeStyle() const {
   return mAttrs.GetMappedDeclarationBlock();
 }

 bool IsPendingMappedAttributeEvaluation() const {
   return mAttrs.IsPendingMappedAttributeEvaluation();
 }

 void SetMappedDeclarationBlock(already_AddRefed<StyleLockedDeclarationBlock>);

 /**
  * InlineStyleDeclarationWillChange is called before SetInlineStyleDeclaration
  * so that the element implementation can access the old style attribute
  * value.
  */
 virtual void InlineStyleDeclarationWillChange(MutationClosureData& aData);

 /**
  * Set the inline style declaration for this element.
  */
 virtual nsresult SetInlineStyleDeclaration(DeclarationBlock& aDeclaration,
                                            MutationClosureData& aData);

 /**
  * Get the SMIL override style declaration for this element. If the
  * rule hasn't been created, this method simply returns null.
  */
 DeclarationBlock* GetSMILOverrideStyleDeclaration();

 /**
  * Set the SMIL override style declaration for this element. This method will
  * notify the document's pres context, so that the style changes will be
  * noticed.
  */
 void SetSMILOverrideStyleDeclaration(DeclarationBlock&);

 /**
  * Returns a new SMILAttr that allows the caller to animate the given
  * attribute on this element.
  */
 virtual UniquePtr<SMILAttr> GetAnimatedAttr(int32_t aNamespaceID,
                                             nsAtom* aName);

 /**
  * Get the SMIL override style for this element. This is a style declaration
  * that is applied *after* the inline style, and it can be used e.g. to store
  * animated style values.
  *
  * Note: This method is analogous to the 'GetStyle' method in
  * nsGenericHTMLElement and nsStyledElement.
  */
 nsDOMCSSAttributeDeclaration* SMILOverrideStyle();

 /**
  * Returns if the element is labelable as per HTML specification.
  */
 virtual bool IsLabelable() const;

 /**
  * Returns if the element is interactive content as per HTML specification.
  */
 virtual bool IsInteractiveHTMLContent() const;

 /**
  * Is the attribute named aAttribute a mapped attribute?
  */
 NS_IMETHOD_(bool) IsAttributeMapped(const nsAtom* aAttribute) const;

 nsresult BindToTree(BindContext&, nsINode& aParent) override;
 void UnbindFromTree(UnbindContext&) override;
 using nsIContent::UnbindFromTree;

 virtual nsMapRuleToAttributesFunc GetAttributeMappingFunction() const;
 static void MapNoAttributesInto(mozilla::MappedDeclarationsBuilder&);

 /**
  * Get a hint that tells the style system what to do when
  * an attribute on this node changes, if something needs to happen
  * in response to the change *other* than the result of what is
  * mapped into style data via any type of style rule.
  */
 virtual nsChangeHint GetAttributeChangeHint(const nsAtom* aAttribute,
                                             AttrModType aModType) const;

 inline Directionality GetDirectionality() const {
   ElementState state = State();
   if (state.HasState(ElementState::RTL)) {
     return Directionality::Rtl;
   }
   if (state.HasState(ElementState::LTR)) {
     return Directionality::Ltr;
   }
   return Directionality::Unset;
 }

 inline void SetDirectionality(Directionality aDir, bool aNotify) {
   AutoStateChangeNotifier notifier(*this, aNotify);
   RemoveStatesSilently(ElementState::DIR_STATES);
   switch (aDir) {
     case Directionality::Rtl:
       AddStatesSilently(ElementState::RTL);
       break;
     case Directionality::Ltr:
       AddStatesSilently(ElementState::LTR);
       break;
     case Directionality::Unset:
     case Directionality::Auto:
       MOZ_ASSERT_UNREACHABLE("Setting unresolved directionality?");
       break;
   }
 }

 Directionality GetComputedDirectionality() const;

 static const uint32_t kAllServoDescendantBits =
     ELEMENT_HAS_DIRTY_DESCENDANTS_FOR_SERVO |
     ELEMENT_HAS_ANIMATION_ONLY_DIRTY_DESCENDANTS_FOR_SERVO |
     NODE_DESCENDANTS_NEED_FRAMES;

 /**
  * Notes that something in the given subtree of this element needs dirtying,
  * and that all the relevant dirty bits have already been propagated up to the
  * element.
  *
  * This is important because `NoteDirtyForServo` uses the dirty bits to reason
  * about the shape of the tree, so we can't just call into there.
  */
 void NoteDirtySubtreeForServo();

 void NoteDirtyForServo();
 void NoteAnimationOnlyDirtyForServo();
 void NoteDescendantsNeedFramesForServo();

 bool HasDirtyDescendantsForServo() const {
   return HasFlag(ELEMENT_HAS_DIRTY_DESCENDANTS_FOR_SERVO);
 }

 void SetHasDirtyDescendantsForServo() {
   SetFlags(ELEMENT_HAS_DIRTY_DESCENDANTS_FOR_SERVO);
 }

 void UnsetHasDirtyDescendantsForServo() {
   UnsetFlags(ELEMENT_HAS_DIRTY_DESCENDANTS_FOR_SERVO);
 }

 bool HasAnimationOnlyDirtyDescendantsForServo() const {
   return HasFlag(ELEMENT_HAS_ANIMATION_ONLY_DIRTY_DESCENDANTS_FOR_SERVO);
 }

 void SetHasAnimationOnlyDirtyDescendantsForServo() {
   SetFlags(ELEMENT_HAS_ANIMATION_ONLY_DIRTY_DESCENDANTS_FOR_SERVO);
 }

 void UnsetHasAnimationOnlyDirtyDescendantsForServo() {
   UnsetFlags(ELEMENT_HAS_ANIMATION_ONLY_DIRTY_DESCENDANTS_FOR_SERVO);
 }

 bool HasServoData() const { return !!mServoData.Get(); }

 void ClearServoData() { ClearServoData(GetComposedDoc()); }
 void ClearServoData(Document* aDocument);

 PopoverData* GetPopoverData() const {
   const nsExtendedDOMSlots* slots = GetExistingExtendedDOMSlots();
   return slots ? slots->mPopoverData.get() : nullptr;
 }

 PopoverData& EnsurePopoverData() {
   if (auto* popoverData = GetPopoverData()) {
     return *popoverData;
   }
   return CreatePopoverData();
 }

 bool IsPopoverOpenedInMode(PopoverAttributeState aMode) const;
 bool IsPopoverOpen() const;

 void SetAssociatedPopover(nsGenericHTMLElement& aPopover);
 nsGenericHTMLElement* GetAssociatedPopover() const;

 /**
  * https://html.spec.whatwg.org/multipage/popover.html#topmost-popover-ancestor
  */
 Element* GetTopmostPopoverAncestor(PopoverAttributeState aMode,
                                    const Element* aInvoker,
                                    bool isPopover) const;

 ElementAnimationData* GetAnimationData() const {
   if (!MayHaveAnimations()) {
     return nullptr;
   }
   const nsExtendedDOMSlots* slots = GetExistingExtendedDOMSlots();
   return slots ? slots->mAnimations.get() : nullptr;
 }

 ElementAnimationData& EnsureAnimationData() {
   if (auto* anim = GetAnimationData()) {
     return *anim;
   }
   return CreateAnimationData();
 }

private:
 ElementAnimationData& CreateAnimationData();
 PopoverData& CreatePopoverData();

public:
 void ClearPopoverData();

 /**
  * Gets the custom element data used by web components custom element.
  * Custom element data is created at the first attempt to enqueue a callback.
  *
  * @return The custom element data or null if none.
  */
 CustomElementData* GetCustomElementData() const {
   if (!HasCustomElementData()) {
     return nullptr;
   }

   const nsExtendedDOMSlots* slots = GetExistingExtendedDOMSlots();
   return slots ? slots->mCustomElementData.get() : nullptr;
 }

 /**
  * Sets the custom element data, ownership of the
  * callback data is taken by this element.
  *
  * @param aData The custom element data.
  */
 void SetCustomElementData(UniquePtr<CustomElementData> aData);

 nsTArray<RefPtr<nsAtom>>& EnsureCustomStates();

 /**
  * Gets the custom element definition used by web components custom element.
  *
  * @return The custom element definition or null if element is not a custom
  *         element or custom element is not defined yet.
  */
 CustomElementDefinition* GetCustomElementDefinition() const;

 /**
  * Sets the custom element definition, called when custom element is created
  * or upgraded.
  *
  * @param aDefinition The custom element definition.
  */
 virtual void SetCustomElementDefinition(CustomElementDefinition* aDefinition);

 const AttrArray& GetAttrs() const { return mAttrs; }

 void SetDefined(bool aSet) { SetStates(ElementState::DEFINED, aSet); }

 // AccessibilityRole
 REFLECT_NULLABLE_DOMSTRING_ATTR(Role, role)

 // AriaAttributes
 REFLECT_NULLABLE_ELEMENT_ATTR(AriaActiveDescendantElement,
                               aria_activedescendant)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaAtomic, aria_atomic)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaAutoComplete, aria_autocomplete)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaBrailleLabel, aria_braillelabel)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaBrailleRoleDescription,
                                 aria_brailleroledescription)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaBusy, aria_busy)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaChecked, aria_checked)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaColCount, aria_colcount)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaColIndex, aria_colindex)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaColIndexText, aria_colindextext)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaColSpan, aria_colspan)
 REFLECT_NULLABLE_ELEMENTS_ATTR(AriaControlsElements, aria_controls)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaCurrent, aria_current)
 REFLECT_NULLABLE_ELEMENTS_ATTR(AriaDescribedByElements, aria_describedby)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaDescription, aria_description)
 REFLECT_NULLABLE_ELEMENTS_ATTR(AriaDetailsElements, aria_details)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaDisabled, aria_disabled)
 REFLECT_NULLABLE_ELEMENTS_ATTR(AriaErrorMessageElements, aria_errormessage)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaExpanded, aria_expanded)
 REFLECT_NULLABLE_ELEMENTS_ATTR(AriaFlowToElements, aria_flowto)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaHasPopup, aria_haspopup)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaHidden, aria_hidden)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaInvalid, aria_invalid)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaKeyShortcuts, aria_keyshortcuts)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaLabel, aria_label)
 REFLECT_NULLABLE_ELEMENTS_ATTR(AriaLabelledByElements, aria_labelledby)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaLevel, aria_level)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaLive, aria_live)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaModal, aria_modal)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaMultiLine, aria_multiline)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaMultiSelectable, aria_multiselectable)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaOrientation, aria_orientation)
 REFLECT_NULLABLE_ELEMENTS_ATTR(AriaOwnsElements, aria_owns)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaPlaceholder, aria_placeholder)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaPosInSet, aria_posinset)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaPressed, aria_pressed)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaReadOnly, aria_readonly)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaRelevant, aria_relevant)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaRequired, aria_required)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaRoleDescription, aria_roledescription)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaRowCount, aria_rowcount)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaRowIndex, aria_rowindex)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaRowIndexText, aria_rowindextext)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaRowSpan, aria_rowspan)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaSelected, aria_selected)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaSetSize, aria_setsize)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaSort, aria_sort)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaValueMax, aria_valuemax)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaValueMin, aria_valuemin)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaValueNow, aria_valuenow)
 REFLECT_NULLABLE_DOMSTRING_ATTR(AriaValueText, aria_valuetext)

protected:
 already_AddRefed<ShadowRoot> AttachShadowInternal(ShadowRootMode,
                                                   ErrorResult& aError);

public:
 MOZ_CAN_RUN_SCRIPT
 ScrollContainerFrame* GetScrollContainerFrame(
     nsIFrame** aFrame = nullptr, FlushType aFlushType = FlushType::Layout);

private:
 // Style state computed from element's state and style locks.
 ElementState StyleStateFromLocks() const;

 void NotifyStateChange(ElementState aStates);
 void NotifyStyleStateChange(ElementState aStates);

public:
 struct AutoStateChangeNotifier {
   AutoStateChangeNotifier(Element& aElement, bool aNotify)
       : mElement(aElement), mOldState(aElement.State()), mNotify(aNotify) {}
   ~AutoStateChangeNotifier() {
     if (!mNotify) {
       return;
     }
     ElementState newState = mElement.State();
     if (mOldState != newState) {
       mElement.NotifyStateChange(mOldState ^ newState);
     }
   }

  private:
   Element& mElement;
   const ElementState mOldState;
   const bool mNotify;
 };

 // Method to add state bits.  This should be called from subclass constructors
 // to set up our event state correctly at construction time, and other places
 // where we don't want to notify a state change, or there's an
 // AutoStateChangeNotifier on the stack.
 void AddStatesSilently(ElementState aStates) { mState |= aStates; }
 // Method to remove state bits.  This should be called from subclass
 // constructors to set up our event state correctly at construction time and
 // other places where we don't want to notify a state change.
 void RemoveStatesSilently(ElementState aStates) { mState &= ~aStates; }
 // Methods to add state bits, potentially notifying. These will handle setting
 // up script blockers when they notify, so no need to do it in the callers
 // unless desired. States passed here must only be those in
 // EXTERNALLY_MANAGED_STATES.
 void AddStates(ElementState aStates, bool aNotify = true) {
   ElementState old = mState;
   AddStatesSilently(aStates);
   if (aNotify && old != mState) {
     NotifyStateChange(old ^ mState);
   }
 }
 void RemoveStates(ElementState aStates, bool aNotify = true) {
   ElementState old = mState;
   RemoveStatesSilently(aStates);
   if (aNotify && old != mState) {
     NotifyStateChange(old ^ mState);
   }
 }
 void SetStates(ElementState aStates, bool aSet, bool aNotify = true) {
   if (aSet) {
     AddStates(aStates, aNotify);
   } else {
     RemoveStates(aStates, aNotify);
   }
 }
 void ToggleStates(ElementState aStates, bool aNotify) {
   mState ^= aStates;
   if (aNotify) {
     NotifyStateChange(aStates);
   }
 }

 void UpdateEditableState(bool aNotify) override;
 // Makes sure that the READONLY/READWRITE flags are in sync.
 void UpdateReadOnlyState(bool aNotify);
 // Form controls and non-form controls should have different :read-only /
 // :read-write behavior. This is what effectively controls it.
 virtual bool IsReadOnlyInternal() const;

 /**
  * Normalizes an attribute name and returns it as a nodeinfo if an attribute
  * with that name exists. This method is intended for character case
  * conversion if the content object is case insensitive (e.g. HTML). Returns
  * the nodeinfo of the attribute with the specified name if one exists or
  * null otherwise.
  *
  * @param aStr the unparsed attribute string
  * @return the node info. May be nullptr.
  */
 already_AddRefed<mozilla::dom::NodeInfo> GetExistingAttrNameFromQName(
     const nsAString& aStr) const;

 /**
  * Helper for SetAttr/SetParsedAttr. This method will return true if aNotify
  * is true, this is a custom element, the attribute is currently set, and the
  * new value that is about to be set is different to the current value. As a
  * perf optimization the new and old values will not actually be compared if
  * we aren't notifying (in which case it's cheap to just return false and let
  * the caller go ahead and set the value).
  * @param aOldValue [out] Set to the old value of the attribute, but only if
  *   there are event listeners. If set, the type of aOldValue will be either
  *   nsAttrValue::eString or nsAttrValue::eAtom.
  * @param aModType [out] Set to AttrModType::Modification or to
  *   AttrModType::Addition, but only if this helper returns true
  * @param aOldValueSet [out] Indicates whether an old attribute value has been
  *   stored in aOldValue. The bool will be set to true if a value was stored.
  */
 bool MaybeCheckSameAttrVal(int32_t aNamespaceID, const nsAtom* aName,
                            const nsAtom* aPrefix,
                            const nsAttrValueOrString& aValue, bool aNotify,
                            nsAttrValue& aOldValue, AttrModType* aModType,
                            bool* aOldValueSet);

 /**
  * Notifies mutation observers if aNotify is true, there are mutation
  * observers, and the attribute value is changing.
  *
  * @param aNamespaceID The namespace of the attribute
  * @param aName The local name of the attribute
  * @param aPrefix The prefix of the attribute
  * @param aValue The value that the attribute is being changed to
  * @param aNotify If true, mutation listeners will be notified if they exist
  *   and the attribute value is changing
  * @param aOldValue [out] Set to the old value of the attribute, but only if
  *   there are event listeners. If set, the type of aOldValue will be either
  *   nsAttrValue::eString or nsAttrValue::eAtom.
  * @param aModType [out] Set to AttrModType::Modification or to
  *   AttrModType::Addition, but only if this helper returns true
  * @param aOldValueSet [out] Indicates whether an old attribute value has been
  *   stored in aOldValue. The bool will be set to true if a value was stored.
  */
 bool OnlyNotifySameValueSet(int32_t aNamespaceID, nsAtom* aName,
                             nsAtom* aPrefix,
                             const nsAttrValueOrString& aValue, bool aNotify,
                             nsAttrValue& aOldValue, AttrModType* aModType,
                             bool* aOldValueSet);

 /**
  * Sets the class attribute.
  * Assumes that we are not notifying and that the attribute hasn't been
  * set previously.
  */
 nsresult SetClassAttrFromParser(nsAtom* aValue);

 // aParsedValue receives the old value of the attribute. That's useful if
 // either the input or output value of aParsedValue is StoresOwnData.
 nsresult SetParsedAttr(int32_t aNameSpaceID, nsAtom* aName, nsAtom* aPrefix,
                        nsAttrValue& aParsedValue, bool aNotify);
 /**
  * Get the current value of the attribute. This returns a form that is
  * suitable for passing back into SetAttr.
  *
  * @param aNameSpaceID the namespace of the attr (defaults to
                        kNameSpaceID_None in the overload that omits this arg)
  * @param aName the name of the attr
  * @param aResult the value (may legitimately be the empty string) [OUT]
  * @returns true if the attribute was set (even when set to empty string)
  *          false when not set.
  * GetAttr is not inlined on purpose, to keep down codesize from all the
  * inlined nsAttrValue bits for C++ callers.
  */
 bool GetAttr(int32_t aNameSpaceID, const nsAtom* aName,
              nsAString& aResult) const;
 bool GetAttr(const nsAtom* aName, nsAString& aResult) const;

 /**
  * Determine if an attribute has been set (empty string or otherwise).
  *
  * @param aNameSpaceId the namespace id of the attribute (defaults to
                        kNameSpaceID_None in the overload that omits this arg)
  * @param aAttr the attribute name
  * @return whether an attribute exists
  */
 inline bool HasAttr(int32_t aNameSpaceID, const nsAtom* aName) const {
   return mAttrs.HasAttr(aNameSpaceID, aName);
 }

 bool HasAttr(const nsAtom* aAttr) const { return mAttrs.HasAttr(aAttr); }

 /**
  * Determine if an attribute has been set to a non-empty string value. If the
  * attribute is not set at all, this will return false.
  *
  * @param aNameSpaceId the namespace id of the attribute (defaults to
  *                     kNameSpaceID_None in the overload that omits this arg)
  * @param aAttr the attribute name
  */
 inline bool HasNonEmptyAttr(int32_t aNameSpaceID, const nsAtom* aName) const;

 bool HasNonEmptyAttr(const nsAtom* aAttr) const {
   return HasNonEmptyAttr(kNameSpaceID_None, aAttr);
 }

 /**
  * Test whether this Element's given attribute has the given value.  If the
  * attribute is not set at all, this will return false.
  *
  * @param aNameSpaceID The namespace ID of the attribute.  Must not
  *                     be kNameSpaceID_Unknown.
  * @param aName The name atom of the attribute.  Must not be null.
  * @param aValue The value to compare to.
  * @param aCaseSensitive Whether to do a case-sensitive compare on the value.
  */
 inline bool AttrValueIs(int32_t aNameSpaceID, const nsAtom* aName,
                         const nsAString& aValue,
                         nsCaseTreatment aCaseSensitive) const;

 /**
  * Test whether this Element's given attribute has the given value.  If the
  * attribute is not set at all, this will return false.
  *
  * @param aNameSpaceID The namespace ID of the attribute.  Must not
  *                     be kNameSpaceID_Unknown.
  * @param aName The name atom of the attribute.  Must not be null.
  * @param aValue The value to compare to.  Must not be null.
  * @param aCaseSensitive Whether to do a case-sensitive compare on the value.
  */
 bool AttrValueIs(int32_t aNameSpaceID, const nsAtom* aName,
                  const nsAtom* aValue, nsCaseTreatment aCaseSensitive) const;

 /**
  * Check whether this Element's given attribute has one of a given list of
  * values. If there is a match, we return the index in the list of the first
  * matching value. If there was no attribute at all, then we return
  * ATTR_MISSING. If there was an attribute but it didn't match, we return
  * ATTR_VALUE_NO_MATCH. A non-negative result always indicates a match.
  *
  * @param aNameSpaceID The namespace ID of the attribute.  Must not
  *                     be kNameSpaceID_Unknown.
  * @param aName The name atom of the attribute.  Must not be null.
  * @param aValues a nullptr-terminated array of pointers to atom values to
  * test against.
  * @param aCaseSensitive Whether to do a case-sensitive compare on the values.
  * @return ATTR_MISSING, ATTR_VALUE_NO_MATCH or the non-negative index
  * indicating the first value of aValues that matched
  */
 using AttrValuesArray = AttrArray::AttrValuesArray;
 int32_t FindAttrValueIn(int32_t aNameSpaceID, const nsAtom* aName,
                         AttrArray::AttrValuesArray* aValues,
                         nsCaseTreatment aCaseSensitive) const;

 /**
  * Set attribute values. All attribute values are assumed to have a
  * canonical string representation that can be used for these
  * methods. The SetAttr method is assumed to perform a translation
  * of the canonical form into the underlying content specific
  * form.
  *
  * @param aNameSpaceID the namespace of the attribute
  * @param aName the name of the attribute
  * @param aValue the value to set
  * @param aNotify specifies how whether or not the document should be
  *        notified of the attribute change.
  */
 nsresult SetAttr(int32_t aNameSpaceID, nsAtom* aName, const nsAString& aValue,
                  bool aNotify) {
   return SetAttr(aNameSpaceID, aName, nullptr, aValue, aNotify);
 }
 nsresult SetAttr(int32_t aNameSpaceID, nsAtom* aName, nsAtom* aPrefix,
                  const nsAString& aValue, bool aNotify) {
   return SetAttr(aNameSpaceID, aName, aPrefix, aValue, nullptr, aNotify);
 }
 nsresult SetAttr(int32_t aNameSpaceID, nsAtom* aName, const nsAString& aValue,
                  nsIPrincipal* aTriggeringPrincipal, bool aNotify) {
   return SetAttr(aNameSpaceID, aName, nullptr, aValue, aTriggeringPrincipal,
                  aNotify);
 }

 /**
  * Set attribute values. All attribute values are assumed to have a
  * canonical String representation that can be used for these
  * methods. The SetAttr method is assumed to perform a translation
  * of the canonical form into the underlying content specific
  * form.
  *
  * @param aNameSpaceID the namespace of the attribute
  * @param aName the name of the attribute
  * @param aPrefix the prefix of the attribute
  * @param aValue the value to set
  * @param aMaybeScriptedPrincipal the principal of the scripted caller
  * responsible for setting the attribute, or null if no scripted caller can be
  *        determined. A null value here does not guarantee that there is no
  *        scripted caller, but a non-null value does guarantee that a scripted
  *        caller with the given principal is directly responsible for the
  *        attribute change.
  * @param aNotify specifies how whether or not the document should be
  *        notified of the attribute change.
  */
 nsresult SetAttr(int32_t aNameSpaceID, nsAtom* aName, nsAtom* aPrefix,
                  const nsAString& aValue,
                  nsIPrincipal* aMaybeScriptedPrincipal, bool aNotify);

 nsresult SetAttr(int32_t aNameSpaceID, nsAtom* aName, nsAtom* aPrefix,
                  nsAtom* aValue, nsIPrincipal* aMaybeScriptedPrincipal,
                  bool aNotify);

 /**
  * Remove an attribute so that it is no longer explicitly specified.
  *
  * @param aNameSpaceID the namespace id of the attribute
  * @param aName the name of the attribute to unset
  * @param aNotify specifies whether or not the document should be
  * notified of the attribute change
  */
 nsresult UnsetAttr(int32_t aNameSpaceID, nsAtom* aName, bool aNotify);

 /**
  * Swap an attribute value. This is a public wrapper that ensures bloom
  * filter updates are performed correctly. For kNameSpaceID_None attributes,
  * this will automatically update the bloom filter and propagate changes to
  * parent elements.
  *
  * @param aLocalName the local name of the attribute
  * @param aValue the value to swap (will contain old value on return)
  * @param aHadValue set to true if attribute existed, false otherwise
  */
 nsresult SetAndSwapAttr(nsAtom* aLocalName, nsAttrValue& aValue,
                         bool* aHadValue);

 /**
  * Swap an attribute value. This is a public wrapper that ensures bloom
  * filter updates are performed correctly. For kNameSpaceID_None attributes,
  * this will automatically update the bloom filter and propagate changes to
  * parent elements.
  *
  * @param aName the node info of the attribute
  * @param aValue the value to swap (will contain old value on return)
  * @param aHadValue set to true if attribute existed, false otherwise
  */
 nsresult SetAndSwapAttr(mozilla::dom::NodeInfo* aName, nsAttrValue& aValue,
                         bool* aHadValue);

 /**
  * Get the namespace / name / prefix of a given attribute.
  *
  * @param   aIndex the index of the attribute name
  * @returns The name at the given index.
  * @note    The document returned by NodeInfo()->GetDocument() (if one is
  *          present) is *not* necessarily the owner document of the element.
  * @note    The pointer returned by this function is only valid until the
  *          next call of either GetAttrNameAt or SetAttr on the element.
  * @note    This will crash if the index is invalid.
  */
 const nsAttrName* GetAttrNameAt(uint32_t aIndex) const {
   return mAttrs.GetSafeAttrNameAt(aIndex);
 }

 /**
  * Same as above, but does not do out-of-bounds checks!
  */
 const nsAttrName* GetUnsafeAttrNameAt(uint32_t aIndex) const {
   return mAttrs.AttrNameAt(aIndex);
 }

 /**
  * A fallible overload of GetAttrNameAt.
  */
 [[nodiscard]] bool GetAttrNameAt(uint32_t aIndex,
                                  const nsAttrName** aResult) const {
   return mAttrs.GetSafeAttrNameAt(aIndex, aResult);
 }

 /**
  * Gets the attribute info (name and value) for this element at a given index.
  */
 BorrowedAttrInfo GetAttrInfoAt(uint32_t aIndex) const {
   if (aIndex >= mAttrs.AttrCount()) {
     return BorrowedAttrInfo(nullptr, nullptr);
   }

   return mAttrs.AttrInfoAt(aIndex);
 }

 /**
  * Get the number of all specified attributes.
  *
  * @return the number of attributes
  */
 uint32_t GetAttrCount() const { return mAttrs.AttrCount(); }

 /**
  * Get the class list of this element (this corresponds to the value of the
  * class attribute).  This may be null if there are no classes, but that's not
  * guaranteed (e.g. we could have class="").
  */
 const nsAttrValue* GetClasses() const {
   if (!MayHaveClass()) {
     return nullptr;
   }

   if (IsSVGElement()) {
     if (const nsAttrValue* value = GetSVGAnimatedClass()) {
       return value;
     }
   }

   return GetParsedAttr(nsGkAtoms::_class);
 }

#ifdef MOZ_DOM_LIST
 virtual void List(FILE* out = stdout, int32_t aIndent = 0) const override {
   List(out, aIndent, ""_ns);
 }
 virtual void DumpContent(FILE* out, int32_t aIndent,
                          bool aDumpAll) const override;
 void List(FILE* out, int32_t aIndent, const nsCString& aPrefix) const;
 void ListAttributes(FILE* out) const;
#endif

 /**
  * Append to aOutDescription a string describing the element and its
  * attributes.
  * If aShort is true, only the id and class attributes will be listed.
  */
 void Describe(nsAString& aOutDescription, bool aShort = false) const;

 /*
  * Attribute Mapping Helpers
  */
 struct MappedAttributeEntry {
   const nsStaticAtom* const attribute;
 };

 /**
  * A common method where you can just pass in a list of maps to check
  * for attribute dependence. Most implementations of
  * IsAttributeMapped should use this function as a default
  * handler.
  */
 template <size_t N>
 static bool FindAttributeDependence(
     const nsAtom* aAttribute, const MappedAttributeEntry* const (&aMaps)[N]) {
   return FindAttributeDependence(aAttribute, aMaps, N);
 }

 // https://html.spec.whatwg.org/#attr-button-command
 enum class Command : uint8_t {
   Invalid,
   Custom,
   TogglePopover,
   ShowPopover,
   HidePopover,
   ShowModal,
   RequestClose,
   Toggle,
   Close,
   Open,
 };

 virtual bool IsValidCommandAction(Command aCommand) const { return false; }

 /**
  * Elements can provide their own default behaviours for "Invoke" (see
  * command/commandfor attributes).
  * If the action is not recognised, they can choose to ignore it and `return
  * false`. If an action is recognised then they should `return true` to
  * indicate to sub-classes that this has been handled and no further steps
  * should be run.
  */
 MOZ_CAN_RUN_SCRIPT virtual bool HandleCommandInternal(Element* aSource,
                                                       Command aCommand,
                                                       ErrorResult& aRv) {
   return false;
 }

private:
 void DescribeAttribute(uint32_t index, nsAString& aOutDescription) const;

 static bool FindAttributeDependence(const nsAtom* aAttribute,
                                     const MappedAttributeEntry* const aMaps[],
                                     uint32_t aMapCount);

 bool HasSharedRoot(const Element* aElement) const;

 Element* GetElementByIdInDocOrSubtree(nsAtom* aID) const;

protected:
 inline bool GetAttr(const nsAtom* aName, DOMString& aResult) const {
   MOZ_ASSERT(aResult.IsEmpty(), "Should have empty string coming in");
   const nsAttrValue* val = mAttrs.GetAttr(aName);
   if (!val) {
     return false;  // DOMString comes pre-emptied.
   }
   val->ToString(aResult);
   return true;
 }

 inline bool GetAttr(int32_t aNameSpaceID, const nsAtom* aName,
                     DOMString& aResult) const {
   MOZ_ASSERT(aResult.IsEmpty(), "Should have empty string coming in");
   const nsAttrValue* val = mAttrs.GetAttr(aName, aNameSpaceID);
   if (!val) {
     return false;  // DOMString comes pre-emptied.
   }
   val->ToString(aResult);
   return true;
 }

public:
 bool HasAttrs() const { return mAttrs.HasAttrs(); }

 inline bool GetAttr(const nsAString& aName, DOMString& aResult) const {
   MOZ_ASSERT(aResult.IsEmpty(), "Should have empty string coming in");
   const nsAttrValue* val = mAttrs.GetAttr(aName);
   if (val) {
     val->ToString(aResult);
     return true;
   }
   // else DOMString comes pre-emptied.
   return false;
 }

 // Note, this does not notify about the removal.
 void ClearAttributes() { mAttrs.Clear(); }

 void GetTagName(nsAString& aTagName) const { aTagName = NodeName(); }
 void GetId(nsAString& aId) const { GetAttr(nsGkAtoms::id, aId); }
 void GetId(DOMString& aId) const { GetAttr(nsGkAtoms::id, aId); }
 void SetId(const nsAString& aId) {
   SetAttr(kNameSpaceID_None, nsGkAtoms::id, aId, true);
 }
 void GetClassName(nsAString& aClassName) {
   GetAttr(nsGkAtoms::_class, aClassName);
 }
 void GetClassName(DOMString& aClassName) {
   GetAttr(nsGkAtoms::_class, aClassName);
 }
 void SetClassName(const nsAString& aClassName) {
   SetAttr(kNameSpaceID_None, nsGkAtoms::_class, aClassName, true);
 }

 nsDOMTokenList* ClassList();
 nsDOMTokenList* Part();

 nsDOMAttributeMap* Attributes();

 void GetAttributeNames(nsTArray<nsString>& aResult);

 void GetAttribute(const nsAString& aName, nsAString& aReturn) {
   DOMString str;
   GetAttribute(aName, str);
   str.ToString(aReturn);
 }

 void GetAttribute(const nsAString& aName, DOMString& aReturn);
 void GetAttributeNS(const nsAString& aNamespaceURI,
                     const nsAString& aLocalName, nsAString& aReturn);
 bool ToggleAttribute(const nsAString& aName, const Optional<bool>& aForce,
                      nsIPrincipal* aTriggeringPrincipal, ErrorResult& aError);
 void SetAttribute(const nsAString& aName, const nsAString& aValue,
                   nsIPrincipal* aTriggeringPrincipal, ErrorResult& aError);
 void SetAttributeNS(const nsAString& aNamespaceURI,
                     const nsAString& aLocalName, const nsAString& aValue,
                     nsIPrincipal* aTriggeringPrincipal, ErrorResult& aError);
 void SetAttribute(const nsAString& aName, const nsAString& aValue,
                   ErrorResult& aError) {
   SetAttribute(aName, aValue, nullptr, aError);
 }

 MOZ_CAN_RUN_SCRIPT void SetAttribute(
     const nsAString& aName,
     const TrustedHTMLOrTrustedScriptOrTrustedScriptURLOrString& aValue,
     nsIPrincipal* aTriggeringPrincipal, ErrorResult& aError);
 MOZ_CAN_RUN_SCRIPT void SetAttributeNS(
     const nsAString& aNamespaceURI, const nsAString& aLocalName,
     const TrustedHTMLOrTrustedScriptOrTrustedScriptURLOrString& aValue,
     nsIPrincipal* aTriggeringPrincipal, ErrorResult& aError);
 MOZ_CAN_RUN_SCRIPT void SetAttribute(
     const nsAString& aName,
     const TrustedHTMLOrTrustedScriptOrTrustedScriptURLOrString& aValue,
     ErrorResult& aError) {
   SetAttribute(aName, aValue, nullptr, aError);
 }

 /**
  * This method creates a principal that subsumes this element's NodePrincipal
  * and which has flags set for elevated permissions that devtools needs to
  * operate on this element. The principal returned by this method is used by
  * various devtools methods to permit otherwise blocked operations, without
  * changing any other restrictions the NodePrincipal might have.
  */
 already_AddRefed<nsIPrincipal> CreateDevtoolsPrincipal();
 void SetAttributeDevtools(const nsAString& aName, const nsAString& aValue,
                           ErrorResult& aError);
 void SetAttributeDevtoolsNS(const nsAString& aNamespaceURI,
                             const nsAString& aLocalName,
                             const nsAString& aValue, ErrorResult& aError);

 void RemoveAttribute(const nsAString& aName, ErrorResult& aError);
 void RemoveAttributeNS(const nsAString& aNamespaceURI,
                        const nsAString& aLocalName, ErrorResult& aError);
 bool HasAttribute(const nsAString& aName) const {
   return InternalGetAttrNameFromQName(aName) != nullptr;
 }
 bool HasAttributeNS(const nsAString& aNamespaceURI,
                     const nsAString& aLocalName) const;
 bool HasAttributes() const { return HasAttrs(); }
 Element* Closest(const nsACString& aSelector, ErrorResult& aResult);
 bool Matches(const nsACString& aSelector, ErrorResult& aError);
 already_AddRefed<nsIHTMLCollection> GetElementsByTagName(
     const nsAString& aQualifiedName);
 already_AddRefed<nsIHTMLCollection> GetElementsByTagNameNS(
     const nsAString& aNamespaceURI, const nsAString& aLocalName,
     ErrorResult& aError);
 already_AddRefed<nsIHTMLCollection> GetElementsByClassName(
     const nsAString& aClassNames);

 /**
  * Returns attribute associated element for the given attribute name, see
  * https://html.spec.whatwg.org/multipage/common-dom-interfaces.html#attr-associated-element
  */
 Element* GetAttrAssociatedElement(nsAtom* aAttr) const;
 void GetAttrAssociatedElements(
     nsAtom* aAttr, bool* aUseCachedValue,
     Nullable<nsTArray<RefPtr<Element>>>& aElements);

 /**
  * Sets an attribute element for the given attribute.
  * https://html.spec.whatwg.org/multipage/common-dom-interfaces.html#explicitly-set-attr-element
  */
 void ExplicitlySetAttrElement(nsAtom* aAttr, Element* aElement);
 void ExplicitlySetAttrElements(
     nsAtom* aAttr,
     const Nullable<Sequence<OwningNonNull<Element>>>& aElements);

 void ClearExplicitlySetAttrElement(nsAtom*);
 void ClearExplicitlySetAttrElements(nsAtom*);

 /**
  * Gets the attribute element for the given attribute.
  * https://html.spec.whatwg.org/multipage/common-dom-interfaces.html#explicitly-set-attr-element
  * Unlike GetAttrAssociatedElement, this returns the target even if it isn't
  * a descendant of any of this element's shadow-including ancestors. It also
  * doesn't attempt to retrieve an element using a string id set in the content
  * attribute.
  */
 Element* GetExplicitlySetAttrElement(nsAtom* aAttr) const;

 /**
  * Gets the attribute elements for the given attribute. Unlike
  * GetAttrAssociatedElements, this returns an uncached array of explicitly set
  * elements without checking if they are a descendant of any of this element's
  * shadow-including ancestors. It also does not attempt to retrieve elements
  * using the ids set in the content attribute.
  */
 void GetExplicitlySetAttrElements(nsAtom* aAttr,
                                   nsTArray<Element*>& aElements) const;

 PseudoStyleType GetPseudoElementType() const {
   nsresult rv = NS_OK;
   auto raw = GetProperty(nsGkAtoms::pseudoProperty, &rv);
   if (rv == NS_PROPTABLE_PROP_NOT_THERE) {
     return PseudoStyleType::NotPseudo;
   }
   return PseudoStyleType(reinterpret_cast<uintptr_t>(raw));
 }

 void SetPseudoElementType(PseudoStyleType aPseudo) {
   static_assert(sizeof(PseudoStyleType) <= sizeof(uintptr_t),
                 "Need to be able to store this in a void*");
   MOZ_ASSERT(PseudoStyle::IsPseudoElement(aPseudo));
   SetProperty(nsGkAtoms::pseudoProperty, reinterpret_cast<void*>(aPseudo));
 }

 /**
  * Return an array of all elements in the subtree rooted at this
  * element that have grid container frames. This does not include
  * pseudo-elements.
  */
 void GetElementsWithGrid(nsTArray<RefPtr<Element>>& aElements);

 /**
  * Provide a direct way to determine if this Element has visible
  * scrollbars. Flushes layout.
  */
 MOZ_CAN_RUN_SCRIPT bool HasVisibleScrollbars();

 /**
  * Get an editor which handles user inputs when this element has focus.
  * If this is a text control, return a TextEditor if it's already created and
  * it's not in the design mode.
  * If this is editable, return HTMLEditor which should've already been
  * created.
  * Otherwise, return nullptr.
  */
 EditorBase* GetExtantEditor() const;

private:
 /**
  * Implement the algorithm specified at
  * https://dom.spec.whatwg.org/#insert-adjacent for both
  * |insertAdjacentElement()| and |insertAdjacentText()| APIs.
  */
 nsINode* InsertAdjacent(const nsAString& aWhere, nsINode* aNode,
                         ErrorResult& aError);

public:
 Element* InsertAdjacentElement(const nsAString& aWhere, Element& aElement,
                                ErrorResult& aError);

 void InsertAdjacentText(const nsAString& aWhere, const nsAString& aData,
                         ErrorResult& aError);

 void SetPointerCapture(int32_t aPointerId, ErrorResult& aError);
 void ReleasePointerCapture(int32_t aPointerId, ErrorResult& aError);
 bool HasPointerCapture(long aPointerId);
 void SetCapture(bool aRetargetToElement);

 void SetCaptureAlways(bool aRetargetToElement);

 void ReleaseCapture();

 already_AddRefed<Promise> RequestFullscreen(CallerType, ErrorResult&);
 void RequestPointerLock(CallerType aCallerType);
 Attr* GetAttributeNode(const nsAString& aName);
 MOZ_CAN_RUN_SCRIPT already_AddRefed<Attr> SetAttributeNode(
     Attr& aNewAttr, nsIPrincipal* aSubjectPrincipal, ErrorResult& aError);
 already_AddRefed<Attr> RemoveAttributeNode(Attr& aOldAttr,
                                            ErrorResult& aError);
 Attr* GetAttributeNodeNS(const nsAString& aNamespaceURI,
                          const nsAString& aLocalName);
 MOZ_CAN_RUN_SCRIPT already_AddRefed<Attr> SetAttributeNodeNS(
     Attr& aNewAttr, nsIPrincipal* aSubjectPrincipal, ErrorResult& aError);

 MOZ_CAN_RUN_SCRIPT already_AddRefed<DOMRectList> GetClientRects();
 MOZ_CAN_RUN_SCRIPT already_AddRefed<DOMRect> GetBoundingClientRect();

 enum class Loading : uint8_t {
   Eager,
   Lazy,
 };

 Loading LoadingState() const;
 void GetLoading(nsAString& aValue) const;
 bool ParseLoadingAttribute(const nsAString& aValue, nsAttrValue& aResult);

 // https://html.spec.whatwg.org/#potentially-render-blocking
 virtual bool IsPotentiallyRenderBlocking() { return false; }
 bool BlockingContainsRender() const;

 // Shadow DOM v1
 enum class ShadowRootDeclarative : bool { No, Yes };

 MOZ_CAN_RUN_SCRIPT_BOUNDARY
 already_AddRefed<ShadowRoot> AttachShadow(const ShadowRootInit& aInit,
                                           ErrorResult& aError);
 bool CanAttachShadowDOM() const;

 enum class DelegatesFocus : bool { No, Yes };
 enum class ShadowRootClonable : bool { No, Yes };
 enum class ShadowRootSerializable : bool { No, Yes };

 already_AddRefed<ShadowRoot> AttachShadowWithoutNameChecks(
     ShadowRootMode aMode, DelegatesFocus = DelegatesFocus::No,
     SlotAssignmentMode aSlotAssignmentMode = SlotAssignmentMode::Named,
     ShadowRootClonable aClonable = ShadowRootClonable::No,
     ShadowRootSerializable aSerializable = ShadowRootSerializable::No,
     const nsAString& aReferenceTarget = EmptyString());

 // Attach UA Shadow Root if it is not attached.
 enum class NotifyUAWidgetSetup : bool { No, Yes };
 void AttachAndSetUAShadowRoot(NotifyUAWidgetSetup = NotifyUAWidgetSetup::Yes,
                               DelegatesFocus = DelegatesFocus::No);

 // Dispatch an event to UAWidgetsChild, triggering construction
 // or onchange callback on the existing widget.
 void NotifyUAWidgetSetupOrChange();

 enum class UnattachShadowRoot {
   No,
   Yes,
 };

 // Dispatch an event to UAWidgetsChild, triggering UA Widget destruction.
 // and optionally remove the shadow root.
 void NotifyUAWidgetTeardown(UnattachShadowRoot = UnattachShadowRoot::Yes);

 void UnattachShadow();

 ShadowRoot* GetShadowRootByMode() const;
 void SetSlot(const nsAString& aName, ErrorResult& aError);
 void GetSlot(nsAString& aName);

 ShadowRoot* GetShadowRoot() const {
   const nsExtendedDOMSlots* slots = GetExistingExtendedDOMSlots();
   return slots ? slots->mShadowRoot.get() : nullptr;
 }

 const Maybe<float> GetLastRememberedBSize() const {
   const nsExtendedDOMSlots* slots = GetExistingExtendedDOMSlots();
   return slots ? slots->mLastRememberedBSize : Nothing();
 }
 const Maybe<float> GetLastRememberedISize() const {
   const nsExtendedDOMSlots* slots = GetExistingExtendedDOMSlots();
   return slots ? slots->mLastRememberedISize : Nothing();
 }
 bool HasLastRememberedBSize() const {
   return GetLastRememberedBSize().isSome();
 }
 bool HasLastRememberedISize() const {
   return GetLastRememberedISize().isSome();
 }

 const Maybe<ContentRelevancy> GetContentRelevancy() const {
   const auto* slots = GetExistingExtendedDOMSlots();
   return slots ? slots->mContentRelevancy : Nothing();
 }
 void SetContentRelevancy(ContentRelevancy relevancy) {
   ExtendedDOMSlots()->mContentRelevancy = Some(relevancy);
 }

 const Maybe<bool> GetVisibleForContentVisibility() const {
   const auto* slots = GetExistingExtendedDOMSlots();
   return slots ? slots->mVisibleForContentVisibility : Nothing();
 }
 void SetVisibleForContentVisibility(bool visible) {
   ExtendedDOMSlots()->mVisibleForContentVisibility = Some(visible);
 }

 void ClearContentRelevancy() {
   if (auto* slots = GetExistingExtendedDOMSlots()) {
     slots->mContentRelevancy.reset();
     slots->mVisibleForContentVisibility.reset();
     slots->mTemporarilyVisibleForScrolledIntoViewDescendant = false;
   }
 }

 bool TemporarilyVisibleForScrolledIntoViewDescendant() const {
   const auto* slots = GetExistingExtendedDOMSlots();
   return slots && slots->mTemporarilyVisibleForScrolledIntoViewDescendant;
 }

 void SetTemporarilyVisibleForScrolledIntoViewDescendant(bool aVisible) {
   ExtendedDOMSlots()->mTemporarilyVisibleForScrolledIntoViewDescendant =
       aVisible;
 }

 // https://drafts.csswg.org/cssom-view-1/#dom-element-checkvisibility
 MOZ_CAN_RUN_SCRIPT bool CheckVisibility(const CheckVisibilityOptions&);

private:
 // DO NOT USE THIS FUNCTION directly in C++. This function is supposed to be
 // called from JS. Use PresShell::ScrollContentIntoView instead.
 MOZ_CAN_RUN_SCRIPT void ScrollIntoView(const ScrollIntoViewOptions& aOptions);

public:
 MOZ_CAN_RUN_SCRIPT
 // DO NOT USE THIS FUNCTION directly in C++. This function is supposed to be
 // called from JS. Use PresShell::ScrollContentIntoView instead.
 void ScrollIntoView(const BooleanOrScrollIntoViewOptions& aObject);
 MOZ_CAN_RUN_SCRIPT void ScrollTo(double aXScroll, double aYScroll);
 MOZ_CAN_RUN_SCRIPT void ScrollTo(const ScrollToOptions& aOptions);
 MOZ_CAN_RUN_SCRIPT void ScrollBy(double aXScrollDif, double aYScrollDif);
 MOZ_CAN_RUN_SCRIPT void ScrollBy(const ScrollToOptions& aOptions);
 MOZ_CAN_RUN_SCRIPT double ScrollTop();
 MOZ_CAN_RUN_SCRIPT void SetScrollTop(double aScrollTop);
 MOZ_CAN_RUN_SCRIPT double ScrollLeft();
 MOZ_CAN_RUN_SCRIPT void SetScrollLeft(double aScrollLeft);
 MOZ_CAN_RUN_SCRIPT int32_t ScrollWidth();
 MOZ_CAN_RUN_SCRIPT int32_t ScrollHeight();
 MOZ_CAN_RUN_SCRIPT void MozScrollSnap();
 MOZ_CAN_RUN_SCRIPT int32_t ClientTop() {
   return CSSPixel::FromAppUnits(GetClientAreaRect().y).Rounded();
 }
 MOZ_CAN_RUN_SCRIPT int32_t ClientLeft() {
   return CSSPixel::FromAppUnits(GetClientAreaRect().x).Rounded();
 }
 MOZ_CAN_RUN_SCRIPT int32_t ClientWidth() {
   return CSSPixel::FromAppUnits(GetClientAreaRect().Width()).Rounded();
 }
 MOZ_CAN_RUN_SCRIPT int32_t ClientHeight() {
   return CSSPixel::FromAppUnits(GetClientAreaRect().Height()).Rounded();
 }

 MOZ_CAN_RUN_SCRIPT int32_t ScreenX();
 MOZ_CAN_RUN_SCRIPT int32_t ScreenY();
 MOZ_CAN_RUN_SCRIPT already_AddRefed<nsIScreen> GetScreen();

 MOZ_CAN_RUN_SCRIPT double ScrollTopMin();
 MOZ_CAN_RUN_SCRIPT double ScrollTopMax();
 MOZ_CAN_RUN_SCRIPT double ScrollLeftMin();
 MOZ_CAN_RUN_SCRIPT double ScrollLeftMax();

 MOZ_CAN_RUN_SCRIPT double ClientHeightDouble() {
   return CSSPixel::FromAppUnits(GetClientAreaRect().Height());
 }

 MOZ_CAN_RUN_SCRIPT double ClientWidthDouble() {
   return CSSPixel::FromAppUnits(GetClientAreaRect().Width());
 }

 MOZ_CAN_RUN_SCRIPT double CurrentCSSZoom();

 Element* GetOffsetParent() {
   CSSIntRect rcFrame;
   return GetOffsetRect(rcFrame);
 }
 int32_t OffsetTop() {
   CSSIntRect rcFrame;
   GetOffsetRect(rcFrame);
   return rcFrame.y;
 }
 int32_t OffsetLeft() {
   CSSIntRect rcFrame;
   GetOffsetRect(rcFrame);
   return rcFrame.x;
 }
 int32_t OffsetWidth() {
   CSSIntRect rcFrame;
   GetOffsetRect(rcFrame);
   return rcFrame.Width();
 }
 int32_t OffsetHeight() {
   CSSIntRect rcFrame;
   GetOffsetRect(rcFrame);
   return rcFrame.Height();
 }
 /**
  * Get the frame's offset information for offsetTop/Left/Width/Height.
  * Returns the parent the offset is relative to.
  * @note This method flushes pending notifications (FlushType::Layout).
  * @param aRect the offset information [OUT]
  */
 Element* GetOffsetRect(CSSIntRect& aRect);

 // This function will return the block size of first line box, no matter if
 // the box is 'block' or 'inline'. The return unit is pixel. If the element
 // can't get a primary frame, we will return be zero.
 double FirstLineBoxBSize() const;

 already_AddRefed<Flex> GetAsFlexContainer();
 void GetGridFragments(nsTArray<RefPtr<Grid>>& aResult);

 bool HasGridFragments();

 already_AddRefed<DOMMatrixReadOnly> GetTransformToAncestor(
     Element& aAncestor);
 already_AddRefed<DOMMatrixReadOnly> GetTransformToParent();
 already_AddRefed<DOMMatrixReadOnly> GetTransformToViewport();

 already_AddRefed<Animation> Animate(
     JSContext* aContext, JS::Handle<JSObject*> aKeyframes,
     const UnrestrictedDoubleOrKeyframeAnimationOptions& aOptions,
     ErrorResult& aError);

 MOZ_CAN_RUN_SCRIPT
 void GetAnimations(const GetAnimationsOptions& aOptions,
                    nsTArray<RefPtr<Animation>>& aAnimations);

 void GetAnimationsWithoutFlush(const GetAnimationsOptions& aOptions,
                                nsTArray<RefPtr<Animation>>& aAnimations);

 void CloneAnimationsFrom(const Element& aOther);

 virtual void GetInnerHTML(nsAString& aInnerHTML, OOMReporter& aError);

 // https://html.spec.whatwg.org/#dom-parsing-and-serialization:dom-element-innerhtml
 // @param aInnerHTML will always be of type `NullIsEmptyString`.
 void GetInnerHTML(OwningTrustedHTMLOrNullIsEmptyString& aInnerHTML,
                   OOMReporter& aError);

 // https://html.spec.whatwg.org/#dom-parsing-and-serialization:dom-element-innerhtml
 //
 // May only run script if aInnerHTML is a string. If this behavior changes,
 // callees might need adjusting.
 MOZ_CAN_RUN_SCRIPT void SetInnerHTML(
     const TrustedHTMLOrNullIsEmptyString& aInnerHTML,
     nsIPrincipal* aSubjectPrincipal, ErrorResult& aError);

 // Call this method only with trusted, i.e. non-attacker-controlled, strings.
 virtual void SetInnerHTMLTrusted(const nsAString& aInnerHTML,
                                  nsIPrincipal* aSubjectPrincipal,
                                  ErrorResult& aError);

 // @param aOuterHTML will always be of type `NullIsEmptyString`.
 void GetOuterHTML(OwningTrustedHTMLOrNullIsEmptyString& aOuterHTML);

 MOZ_CAN_RUN_SCRIPT void SetOuterHTML(
     const TrustedHTMLOrNullIsEmptyString& aOuterHTML,
     nsIPrincipal* aSubjectPrincipal, ErrorResult& aError);

 MOZ_CAN_RUN_SCRIPT void InsertAdjacentHTML(
     const nsAString& aPosition,
     const TrustedHTMLOrString& aTrustedHTMLOrString,
     nsIPrincipal* aSubjectPrincipal, ErrorResult& aError);

 virtual void SetHTML(const nsAString& aInnerHTML,
                      const SetHTMLOptions& aOptions, ErrorResult& aError);

 MOZ_CAN_RUN_SCRIPT
 virtual void SetHTMLUnsafe(const TrustedHTMLOrString& aHTML,
                            const SetHTMLUnsafeOptions& aOptions,
                            nsIPrincipal* aSubjectPrincipal,
                            ErrorResult& aError);

 void GetHTML(const GetHTMLOptions& aOptions, nsAString& aResult);

 StylePropertyMapReadOnly* ComputedStyleMap();

 //----------------------------------------

 /**
  * Add a script event listener with the given event handler name
  * (like onclick) and with the value as JS
  * @param aEventName the event listener name
  * @param aValue the JS to attach
  * @param aDefer indicates if deferred execution is allowed
  */
 void SetEventHandler(nsAtom* aEventName, const nsAString& aValue,
                      bool aDefer = true);

 /**
  * Do whatever needs to be done when the mouse leaves a link
  */
 nsresult LeaveLink(nsPresContext* aPresContext);

 static bool ShouldBlur(nsIContent* aContent);

 /**
  * Method to create and dispatch a left-click event loosely based on
  * aSourceEvent. If aFullDispatch is true, the event will be dispatched
  * through the full dispatching of the presshell of the aPresContext; if it's
  * false the event will be dispatched only as a DOM event.
  * If aPresContext is nullptr, this does nothing.
  *
  * @param aFlags      Extra flags for the dispatching event.  The true flags
  *                    will be respected.
  */
 MOZ_CAN_RUN_SCRIPT
 static nsresult DispatchClickEvent(nsPresContext* aPresContext,
                                    WidgetInputEvent* aSourceEvent,
                                    nsIContent* aTarget, bool aFullDispatch,
                                    const EventFlags* aFlags,
                                    nsEventStatus* aStatus);

 /**
  * Method to dispatch aEvent to aTarget. If aFullDispatch is true, the event
  * will be dispatched through the full dispatching of the presshell of the
  * aPresContext; if it's false the event will be dispatched only as a DOM
  * event.
  * If aPresContext is nullptr, this does nothing.
  */
 using nsIContent::DispatchEvent;
 MOZ_CAN_RUN_SCRIPT
 static nsresult DispatchEvent(nsPresContext* aPresContext,
                               WidgetEvent* aEvent, nsIContent* aTarget,
                               bool aFullDispatch, nsEventStatus* aStatus);

 bool IsDisplayContents() const {
   return HasServoData() && Servo_Element_IsDisplayContents(this);
 }

 /*
  * https://html.spec.whatwg.org/#being-rendered
  *
  * With a gotcha for display contents:
  *   https://github.com/whatwg/html/issues/1837
  */
 bool IsRendered() const { return GetPrimaryFrame() || IsDisplayContents(); }

 const nsAttrValue* GetParsedAttr(const nsAtom* aAttr) const {
   return mAttrs.GetAttr(aAttr);
 }

 const nsAttrValue* GetParsedAttr(const nsAtom* aAttr,
                                  int32_t aNameSpaceID) const {
   return mAttrs.GetAttr(aAttr, aNameSpaceID);
 }

 /**
  * Returns the attribute map, if there is one.
  *
  * @return existing attribute map or nullptr.
  */
 nsDOMAttributeMap* GetAttributeMap() {
   nsDOMSlots* slots = GetExistingDOMSlots();

   return slots ? slots->mAttributeMap.get() : nullptr;
 }

 void RecompileScriptEventListeners();

 /**
  * Get the attr info for the given namespace ID and attribute name.  The
  * namespace ID must not be kNameSpaceID_Unknown and the name must not be
  * null.  Note that this can only return info on attributes that actually
  * live on this element (and is only virtual to handle XUL prototypes).  That
  * is, this should only be called from methods that only care about attrs
  * that effectively live in mAttrs.
  */
 BorrowedAttrInfo GetAttrInfo(int32_t aNamespaceID,
                              const nsAtom* aName) const {
   NS_ASSERTION(aName, "must have attribute name");
   NS_ASSERTION(aNamespaceID != kNameSpaceID_Unknown,
                "must have a real namespace ID!");

   int32_t index = mAttrs.IndexOfAttr(aName, aNamespaceID);
   if (index < 0) {
     return BorrowedAttrInfo(nullptr, nullptr);
   }

   return mAttrs.AttrInfoAt(index);
 }

 /**
  * Parse a string into an nsAttrValue for a CORS attribute.  This
  * never fails.  The resulting value is an enumerated value whose
  * GetEnumValue() returns one of the above constants.
  */
 static void ParseCORSValue(const nsAString& aValue, nsAttrValue& aResult);

 /**
  * Return the CORS mode for a given string
  */
 static CORSMode StringToCORSMode(const nsAString& aValue);

 /**
  * Return the CORS mode for a given nsAttrValue (which may be null,
  * but if not should have been parsed via ParseCORSValue).
  */
 static CORSMode AttrValueToCORSMode(const nsAttrValue* aValue);

 nsINode* GetScopeChainParent() const override;

 JSObject* WrapNode(JSContext*, JS::Handle<JSObject*> aGivenProto) override;

 /**
  * Locate a TextEditor rooted at this content node, if there is one.
  */
 MOZ_CAN_RUN_SCRIPT_BOUNDARY mozilla::TextEditor* GetTextEditorInternal();

 /**
  * Gets value of boolean attribute. Only works for attributes in null
  * namespace.
  *
  * @param aAttr    name of attribute.
  * @param aValue   Boolean value of attribute.
  */
 bool GetBoolAttr(nsAtom* aAttr) const { return HasAttr(aAttr); }

 /**
  * Sets value of boolean attribute by removing attribute or setting it to
  * the empty string. Only works for attributes in null namespace.
  *
  * @param aAttr    name of attribute.
  * @param aValue   Boolean value of attribute.
  */
 nsresult SetBoolAttr(nsAtom* aAttr, bool aValue);

 /**
  * Gets the enum value string of an attribute and using a default value if
  * the attribute is missing or the string is an invalid enum value.
  *
  * @param aType     the name of the attribute.
  * @param aDefault  the default value if the attribute is missing or invalid.
  * @param aResult   string corresponding to the value [out].
  */
 void GetEnumAttr(nsAtom* aAttr, const char* aDefault,
                  nsAString& aResult) const;

 /**
  * Gets the enum value string of an attribute and using the default missing
  * value if the attribute is missing or the default invalid value if the
  * string is an invalid enum value.
  *
  * @param aType            the name of the attribute.
  * @param aDefaultMissing  the default value if the attribute is missing.  If
                            null and the attribute is missing, aResult will be
                            set to the null DOMString; this only matters for
                            cases in which we're reflecting a nullable string.
  * @param aDefaultInvalid  the default value if the attribute is invalid.
  * @param aResult          string corresponding to the value [out].
  */
 void GetEnumAttr(nsAtom* aAttr, const char* aDefaultMissing,
                  const char* aDefaultInvalid, nsAString& aResult) const;

 /**
  * Unset an attribute.
  */
 void UnsetAttr(nsAtom* aAttr, ErrorResult& aError) {
   aError = UnsetAttr(kNameSpaceID_None, aAttr, true);
 }

 /**
  * Set an attribute in the simplest way possible.
  */
 void SetAttr(nsAtom* aAttr, const nsAString& aValue, ErrorResult& aError) {
   aError = SetAttr(kNameSpaceID_None, aAttr, aValue, true);
 }

 void SetAttr(nsAtom* aAttr, const nsAString& aValue,
              nsIPrincipal* aTriggeringPrincipal, ErrorResult& aError) {
   aError =
       SetAttr(kNameSpaceID_None, aAttr, aValue, aTriggeringPrincipal, true);
 }

 /**
  * Preallocate space in this element's attribute array for the given
  * total number of attributes.
  */
 void TryReserveAttributeCount(uint32_t aAttributeCount);

 void SetParserHadDuplicateAttributeError() {
   SetFlags(ELEMENT_PARSER_HAD_DUPLICATE_ATTR_ERROR);
 }

 /**
  * Set a content attribute via a reflecting nullable string IDL
  * attribute (e.g. a CORS attribute).  If DOMStringIsNull(aValue),
  * this will actually remove the content attribute.
  */
 void SetOrRemoveNullableStringAttr(nsAtom* aName, const nsAString& aValue,
                                    ErrorResult& aError);

 /**
  * Retrieve the ratio of font-size-inflated text font size to computed font
  * size for this element. This will query the element for its primary frame,
  * and then use this to get font size inflation information about the frame.
  *
  * @returns The font size inflation ratio (inflated font size to uninflated
  *          font size) for the primary frame of this element. Returns 1.0
  *          by default if font size inflation is not enabled. Returns -1
  *          if the element does not have a primary frame.
  *
  * @note The font size inflation ratio that is returned is actually the
  *       font size inflation data for the element's _primary frame_, not the
  *       element itself, but for most purposes, this should be sufficient.
  */
 float FontSizeInflation();

 void GetImplementedPseudoElement(nsAString&) const;

 /**
  * Get the pseudo element for this pseudo request (i.e. PseudoStyleType and
  * its function parameter, if any).
  */
 Element* GetPseudoElement(const PseudoStyleRequest&) const;

 ReferrerPolicy GetReferrerPolicyAsEnum() const;
 ReferrerPolicy ReferrerPolicyFromAttr(const nsAttrValue* aValue) const;

 /*
  * Helpers for .dataset.  This is implemented on Element, though only some
  * sorts of elements expose it to JS as a .dataset property
  */
 // Getter, to be called from bindings.
 already_AddRefed<nsDOMStringMap> Dataset();
 // Callback for destructor of dataset to ensure to null out our weak pointer
 // to it.
 void ClearDataset();

 // A number of methods to cast to various XUL interfaces. They return a
 // pointer only if the element implements that interface.
 already_AddRefed<nsIDOMXULButtonElement> AsXULButton();
 already_AddRefed<nsIDOMXULContainerElement> AsXULContainer();
 already_AddRefed<nsIDOMXULContainerItemElement> AsXULContainerItem();
 already_AddRefed<nsIDOMXULControlElement> AsXULControl();
 already_AddRefed<nsIDOMXULMenuListElement> AsXULMenuList();
 already_AddRefed<nsIDOMXULMultiSelectControlElement>
 AsXULMultiSelectControl();
 already_AddRefed<nsIDOMXULRadioGroupElement> AsXULRadioGroup();
 already_AddRefed<nsIDOMXULRelatedElement> AsXULRelated();
 already_AddRefed<nsIDOMXULSelectControlElement> AsXULSelectControl();
 already_AddRefed<nsIDOMXULSelectControlItemElement> AsXULSelectControlItem();
 already_AddRefed<nsIBrowser> AsBrowser();
 already_AddRefed<nsIAutoCompletePopup> AsAutoCompletePopup();

 /**
  * Get the presentation context for this content node.
  * @return the presentation context
  */
 enum PresContextFor { eForComposedDoc, eForUncomposedDoc };
 nsPresContext* GetPresContext(PresContextFor aFor) const;

 /**
  * The method focuses (or activates) element that accesskey is bound to. It is
  * called when accesskey is activated.
  *
  * @param aKeyCausesActivation - if true then element should be activated
  * @param aIsTrustedEvent - if true then event that is cause of accesskey
  *                          execution is trusted.
  * @return an error if the element isn't able to handle the accesskey (caller
  *         would look for the next element to handle it).
  *         a boolean indicates whether the focus moves to the element after
  *         the element handles the accesskey.
  */
 MOZ_CAN_RUN_SCRIPT
 virtual Result<bool, nsresult> PerformAccesskey(bool aKeyCausesActivation,
                                                 bool aIsTrustedEvent) {
   return Err(NS_ERROR_NOT_IMPLEMENTED);
 }

protected:
 // Supported rel values for <form> and anchors.
 static const DOMTokenListSupportedToken sAnchorAndFormRelValues[];

 /*
  * Named-bools for use with SetAttrAndNotify to make call sites easier to
  * read.
  */
 static const bool kNotifyDocumentObservers = true;
 static const bool kDontNotifyDocumentObservers = false;
 static const bool kCallAfterSetAttr = true;
 static const bool kDontCallAfterSetAttr = false;

 /*
  * The supported values of blocking attribute for use with nsDOMTokenList.
  */
 static const DOMTokenListSupportedToken sSupportedBlockingValues[];

 /**
  * Common implementation for SetAttr overloads. Takes a callback to perform
  * the type-specific parsing and value setting.
  */
 template <typename ParseFunc>
 nsresult SetAttrInternal(int32_t aNamespaceID, nsAtom* aName, nsAtom* aPrefix,
                          const nsAttrValueOrString& aValueForComparison,
                          nsIPrincipal* aSubjectPrincipal, bool aNotify,
                          ParseFunc&& aParseFn);

 /**
  * Set attribute and (if needed) notify documentobservers.  This will send the
  * AttributeChanged notification. Callers of this method are responsible for
  * calling AttributeWillChange, since that needs to happen before the new attr
  * value has been set, and in particular before it has been parsed.
  *
  * For the boolean parameters, consider using the named bools above to aid
  * code readability.
  *
  * @param aNamespaceID  namespace of attribute
  * @param aAttribute    local-name of attribute
  * @param aPrefix       aPrefix of attribute
  * @param aOldValue     The old value of the attribute to use as a fallback
  *                      in the cases where the actual old value (i.e.
  *                      its current value) is !StoresOwnData() --- in which
  *                      case the current value is probably already useless.
  *                      If the current value is StoresOwnData() (or absent),
  *                      aOldValue will not be used. aOldValue will only be set
  *                      in certain circumstances (there are mutation
  *                      listeners, element is a custom element, attribute was
  *                      not previously unset). Otherwise it will be null.
  * @param aParsedValue  parsed new value of attribute. Replaced by the
  *                      old value of the attribute. This old value is only
  *                      useful if either it or the new value is StoresOwnData.
  * @param aSubjectPrincipal
  *                      the principal of the scripted caller responsible for
  *                      setting the attribute, or null if no scripted caller
  *                      can be determined. A null value here does not
  *                      guarantee that there is no scripted caller, but a
  *                      non-null value does guarantee that a scripted caller
  *                      with the given principal is directly responsible for
  *                      the attribute change.
  * @param aModType      AttrModType::Modification or AttrModType::Addition.
  * @param aNotify       should we notify document-observers?
  * @param aCallAfterSetAttr should we call AfterSetAttr?
  * @param aComposedDocument The current composed document of the element.
  * @param aGuard        For making sure that this is called with a
  *                      mozAutoDocUpdate instance, this is here.  Specify
  *                      an instance of it which you created for the call.
  */
 nsresult SetAttrAndNotify(int32_t aNamespaceID, nsAtom* aName,
                           nsAtom* aPrefix, const nsAttrValue* aOldValue,
                           nsAttrValue& aParsedValue,
                           nsIPrincipal* aSubjectPrincipal,
                           AttrModType aModType, bool aNotify,
                           bool aCallAfterSetAttr, Document* aComposedDocument,
                           const mozAutoDocUpdate& aGuard);

 /**
  * Convert an attribute string value to attribute type based on the type of
  * attribute.  Called by SetAttr().  Note that at the moment we only do this
  * for attributes in the null namespace (kNameSpaceID_None).
  *
  * @param aNamespaceID the namespace of the attribute to convert
  * @param aAttribute the attribute to convert
  * @param aValue the string value to convert
  * @param aMaybeScriptedPrincipal the principal of the script setting the
  *        attribute, if one can be determined, or null otherwise. As in
  *        AfterSetAttr, a null value does not guarantee that the attribute was
  *        not set by a scripted caller, but a non-null value guarantees that
  *        the attribute was set by a scripted caller with the given principal.
  * @param aResult the nsAttrValue [OUT]
  * @return true if the parsing was successful, false otherwise
  */
 virtual bool ParseAttribute(int32_t aNamespaceID, nsAtom* aAttribute,
                             const nsAString& aValue,
                             nsIPrincipal* aMaybeScriptedPrincipal,
                             nsAttrValue& aResult);

 /**
  * Hook that is called by Element::SetAttr to allow subclasses to
  * deal with attribute sets.  This will only be called after we verify that
  * we're actually doing an attr set and will be called before
  * AttributeWillChange and before ParseAttribute and hence before we've set
  * the new value.
  *
  * @param aNamespaceID the namespace of the attr being set
  * @param aName the localname of the attribute being set
  * @param aValue the value it's being set to represented as either a string or
  *        a parsed nsAttrValue. Alternatively, if the attr is being removed it
  *        will be null.
  * @param aNotify Whether we plan to notify document observers.
  */
 virtual void BeforeSetAttr(int32_t aNamespaceID, nsAtom* aName,
                            const nsAttrValue* aValue, bool aNotify);

 /**
  * Hook that is called by Element::SetAttr to allow subclasses to
  * deal with attribute sets.  This will only be called after we have called
  * SetAndSwapAttr (that is, after we have actually set the attr).  It will
  * always be called under a scriptblocker.
  *
  * @param aNamespaceID the namespace of the attr being set
  * @param aName the localname of the attribute being set
  * @param aValue the value it's being set to.  If null, the attr is being
  *        removed.
  * @param aOldValue the value that the attribute had previously. If null,
  *        the attr was not previously set. This argument may not have the
  *        correct value for SVG elements, or other cases in which the
  *        attribute value doesn't store its own data
  * @param aMaybeScriptedPrincipal the principal of the scripted caller
  *        responsible for setting the attribute, or null if no scripted caller
  *        can be determined, or the attribute is being unset. A null value
  *        here does not guarantee that there is no scripted caller, but a
  *        non-null value does guarantee that a scripted caller with the given
  *        principal is directly responsible for the attribute change.
  * @param aNotify Whether we plan to notify document observers.
  */
 virtual void AfterSetAttr(int32_t aNamespaceID, nsAtom* aName,
                           const nsAttrValue* aValue,
                           const nsAttrValue* aOldValue,
                           nsIPrincipal* aMaybeScriptedPrincipal,
                           bool aNotify);

 /**
  * This function shall be called just before the id attribute changes. It will
  * be called after BeforeSetAttr. If the attribute being changed is not the id
  * attribute, this function does nothing. Otherwise, it will remove the old id
  * from the document's id cache.
  *
  * This must happen after BeforeSetAttr (rather than during) because the
  * the subclasses' calls to BeforeSetAttr may notify on state changes. If they
  * incorrectly determine whether the element had an id, the element may not be
  * restyled properly.
  *
  * @param aNamespaceID the namespace of the attr being set
  * @param aName the localname of the attribute being set
  * @param aValue the new id value. Will be null if the id is being unset.
  */
 void PreIdMaybeChange(int32_t aNamespaceID, nsAtom* aName,
                       const nsAttrValue* aValue);

 /**
  * This function shall be called just after the id attribute changes. It will
  * be called before AfterSetAttr. If the attribute being changed is not the id
  * attribute, this function does nothing. Otherwise, it will add the new id to
  * the document's id cache and properly set the ElementHasID flag.
  *
  * This must happen before AfterSetAttr (rather than during) because the
  * the subclasses' calls to AfterSetAttr may notify on state changes. If they
  * incorrectly determine whether the element now has an id, the element may
  * not be restyled properly.
  *
  * @param aNamespaceID the namespace of the attr being set
  * @param aName the localname of the attribute being set
  * @param aValue the new id value. Will be null if the id is being unset.
  */
 void PostIdMaybeChange(int32_t aNamespaceID, nsAtom* aName,
                        const nsAttrValue* aValue);

 /**
  * Usually, setting an attribute to the value that it already has results in
  * no action. However, in some cases, setting an attribute to its current
  * value should have the effect of, for example, forcing a reload of
  * network data. To address that, this function will be called in this
  * situation to allow the handling of such a case.
  *
  * @param aNamespaceID the namespace of the attr being set
  * @param aName the localname of the attribute being set
  * @param aValue the value it's being set to represented as either a string or
  *        a parsed nsAttrValue.
  * @param aNotify Whether we plan to notify document observers.
  */
 virtual void OnAttrSetButNotChanged(int32_t aNamespaceID, nsAtom* aName,
                                     const nsAttrValueOrString& aValue,
                                     bool aNotify);

 /**
  * Hook to allow subclasses to produce a different EventListenerManager if
  * needed for attachment of attribute-defined handlers
  */
 virtual EventListenerManager* GetEventListenerManagerForAttr(
     nsAtom* aAttrName, bool* aDefer);

 /**
  * Internal hook for converting an attribute name-string to nsAttrName in
  * case there is such existing attribute. aNameToUse can be passed to get
  * name which was used for looking for the attribute (lowercase in HTML).
  */
 const nsAttrName* InternalGetAttrNameFromQName(
     const nsAString& aStr, nsAutoString* aNameToUse = nullptr) const;

 virtual Element* GetNameSpaceElement() override { return this; }

 Attr* GetAttributeNodeNSInternal(const nsAString& aNamespaceURI,
                                  const nsAString& aLocalName);

 inline void RegisterActivityObserver();
 inline void UnregisterActivityObserver();

 /**
  * Add/remove this element to the documents id cache
  */
 void AddToIdTable(nsAtom* aId);
 void RemoveFromIdTable();

 /**
  * Functions to carry out event default actions for links of all types
  * (HTML links, XLinks, SVG "XLinks", etc.)
  */

 /**
  * Check that we meet the conditions to handle a link event
  * and that we are actually on a link.
  *
  * @param aVisitor event visitor
  * @return true if we can handle the link event, false otherwise
  */
 bool CheckHandleEventForLinksPrecondition(EventChainVisitor& aVisitor) const;

 /**
  * Handle status bar updates before they can be cancelled.
  */
 void GetEventTargetParentForLinks(EventChainPreVisitor& aVisitor);

 void DispatchChromeOnlyLinkClickEvent(EventChainPostVisitor& aVisitor);

 /**
  * Handle default actions for link event if the event isn't consumed yet.
  */
 MOZ_CAN_RUN_SCRIPT
 nsresult PostHandleEventForLinks(EventChainPostVisitor& aVisitor);

 mozilla::dom::FetchPriority GetFetchPriority() const;

 static void ParseFetchPriority(const nsAString& aValue, nsAttrValue& aResult);

public:
 /**
  * Check if this element is a link. This matches the CSS definition of the
  * :any-link pseudo-class.
  */
 bool IsLink() const {
   return mState.HasAtLeastOneOfStates(ElementState::VISITED |
                                       ElementState::UNVISITED);
 }

 /**
  * Get a pointer to the full href URI (fully resolved and canonicalized, since
  * it's an nsIURI object) for link elements.
  *
  * @return A pointer to the URI or null if the element is not a link, or it
  *         has no HREF attribute, or the HREF attribute is an invalid URI.
  */
 virtual already_AddRefed<nsIURI> GetHrefURI() const { return nullptr; }

 // Step 2. of
 // <https://html.spec.whatwg.org/multipage/semantics.html#get-an-element's-target>
 //
 // Sanitize targets that look like they contain dangling markup.
 static void SanitizeLinkOrFormTarget(nsAString& aTarget);

 /**
  * <https://html.spec.whatwg.org/multipage/semantics.html#get-an-element's-target>
  * (Excluding <form>)
  *
  * Get the target of this link element. Consumers should established that
  * this element is a link (probably using IsLink) before calling this
  * function (or else why call it?). This method neuters probably markup
  * injection attempts.
  *
  * Note: for HTML this gets the value of the 'target' attribute; for XLink
  * this gets the value of the xlink:_moz_target attribute, or failing that,
  * the value of xlink:show, converted to a suitably equivalent named target
  * (e.g. _blank).
  */
 void GetLinkTarget(nsAString& aTarget);

 virtual void GetLinkTargetImpl(nsAString& aTarget);

 virtual bool Translate() const;

 MOZ_CAN_RUN_SCRIPT
 void FireBeforematchEvent(ErrorResult& aRv);

 void PropagateBloomFilterToParents();
 void UpdateSubtreeBloomFilterForClass(const nsAttrValue* aClassValue);
 void UpdateSubtreeBloomFilterForAttribute(nsAtom* aAttribute);
 uint64_t GetSubtreeBloomFilter() const {
   return mAttrs.GetSubtreeBloomFilter();
 }
#ifdef DEBUG
 void VerifySubtreeBloomFilter() const;
#endif

protected:
 enum class ReparseAttributes { No, Yes };
 /**
  * Copy attributes and state to another element
  * @param aDest the object to copy to
  */
 nsresult CopyInnerTo(Element* aDest,
                      ReparseAttributes = ReparseAttributes::Yes);

 /**
  * Some event handler content attributes have a different name (e.g. different
  * case) from the actual event name.  This function takes an event handler
  * content attribute name and returns the corresponding event name, to be used
  * for adding the actual event listener.
  */
 virtual nsAtom* GetEventNameForAttr(nsAtom* aAttr);

 /**
  * Register/unregister this element to accesskey map if it supports accesskey.
  */
 virtual void RegUnRegAccessKey(bool aDoReg);

private:
#ifdef MOZ_DIAGNOSTIC_ASSERT_ENABLED
 void AssertInvariantsOnNodeInfoChange();
#endif

 /**
  * Slow path for GetClasses, this should only be called for SVG elements.
  */
 const nsAttrValue* GetSVGAnimatedClass() const;

 /**
  * Get this element's client area rect in app units.
  * @return the frame's client area
  */
 MOZ_CAN_RUN_SCRIPT nsRect GetClientAreaRect();

 /** Gets the scroll size as for the scroll{Width,Height} APIs */
 MOZ_CAN_RUN_SCRIPT nsSize GetScrollSize();
 /** Gets the scroll position as for the scroll{Top,Left} APIs */
 MOZ_CAN_RUN_SCRIPT nsPoint GetScrollOrigin();
 /** Gets the scroll range as for the scroll{Top,Left}{Min,Max} APIs */
 MOZ_CAN_RUN_SCRIPT nsRect GetScrollRange();

 /**
  * GetCustomInterface is somewhat like a GetInterface, but it is expected
  * that the implementation is provided by a custom element or via the
  * the XBL implements keyword. To use this, create a public method that
  * wraps a call to GetCustomInterface.
  */
 template <class T>
 void GetCustomInterface(nsGetterAddRefs<T> aResult);

 // Prevent people from doing pointless checks/casts on Element instances.
 void IsElement() = delete;
 void AsElement() = delete;

 // Data members
 ElementState mState;
 // Per-node data managed by Servo.
 //
 // There should not be data on nodes that are not in the flattened tree, or
 // descendants of display: none elements.
 mozilla::RustCell<ServoNodeData*> mServoData;

protected:
 // Array containing all attributes for this element
 AttrArray mAttrs;
};

inline bool Element::HasNonEmptyAttr(int32_t aNameSpaceID,
                                    const nsAtom* aName) const {
 MOZ_ASSERT(aNameSpaceID > kNameSpaceID_Unknown, "Must have namespace");
 MOZ_ASSERT(aName, "Must have attribute name");

 const nsAttrValue* val = mAttrs.GetAttr(aName, aNameSpaceID);
 return val && !val->IsEmptyString();
}

inline bool Element::AttrValueIs(int32_t aNameSpaceID, const nsAtom* aName,
                                const nsAString& aValue,
                                nsCaseTreatment aCaseSensitive) const {
 return mAttrs.AttrValueIs(aNameSpaceID, aName, aValue, aCaseSensitive);
}

inline bool Element::AttrValueIs(int32_t aNameSpaceID, const nsAtom* aName,
                                const nsAtom* aValue,
                                nsCaseTreatment aCaseSensitive) const {
 return mAttrs.AttrValueIs(aNameSpaceID, aName, aValue, aCaseSensitive);
}

}  // namespace dom
}  // namespace mozilla

NON_VIRTUAL_ADDREF_RELEASE(mozilla::dom::Element)

inline mozilla::dom::Element* nsINode::AsElement() {
 MOZ_ASSERT(IsElement());
 return static_cast<mozilla::dom::Element*>(this);
}

inline const mozilla::dom::Element* nsINode::AsElement() const {
 MOZ_ASSERT(IsElement());
 return static_cast<const mozilla::dom::Element*>(this);
}

inline mozilla::dom::Element* nsINode::GetParentElement() const {
 return mozilla::dom::Element::FromNodeOrNull(mParent);
}

inline mozilla::dom::Element* nsINode::GetPreviousElementSibling() const {
 nsIContent* previousSibling = GetPreviousSibling();
 while (previousSibling) {
   if (previousSibling->IsElement()) {
     return previousSibling->AsElement();
   }
   previousSibling = previousSibling->GetPreviousSibling();
 }

 return nullptr;
}

inline mozilla::dom::ShadowRoot* nsINode::GetShadowRoot() const {
 return IsElement() ? AsElement()->GetShadowRoot() : nullptr;
}

inline mozilla::dom::Element* nsINode::GetAsElementOrParentElement() const {
 return IsElement() ? const_cast<mozilla::dom::Element*>(AsElement())
                    : GetParentElement();
}

inline mozilla::dom::Element* nsINode::GetNextElementSibling() const {
 nsIContent* nextSibling = GetNextSibling();
 while (nextSibling) {
   if (nextSibling->IsElement()) {
     return nextSibling->AsElement();
   }
   nextSibling = nextSibling->GetNextSibling();
 }

 return nullptr;
}

/**
* Macros to implement Clone(). _elementName is the class for which to implement
* Clone.
*/
#define NS_IMPL_ELEMENT_CLONE(_elementName, ...)                    \
 nsresult _elementName::Clone(mozilla::dom::NodeInfo* aNodeInfo,   \
                              nsINode** aResult) const {           \
   *aResult = nullptr;                                             \
   RefPtr<_elementName> it = new (aNodeInfo->NodeInfoManager())    \
       _elementName(do_AddRef(aNodeInfo), ##__VA_ARGS__);          \
   nsresult rv = const_cast<_elementName*>(this)->CopyInnerTo(it); \
   if (NS_SUCCEEDED(rv)) {                                         \
     it.forget(aResult);                                           \
   }                                                               \
   return rv;                                                      \
 }

#define NS_IMPL_ELEMENT_CLONE_WITH_INIT(_elementName, ...)           \
 nsresult _elementName::Clone(mozilla::dom::NodeInfo* aNodeInfo,    \
                              nsINode** aResult) const {            \
   *aResult = nullptr;                                              \
   RefPtr<_elementName> it = new (aNodeInfo->NodeInfoManager())     \
       _elementName(do_AddRef(aNodeInfo), ##__VA_ARGS__);           \
   nsresult rv = it->Init();                                        \
   nsresult rv2 = const_cast<_elementName*>(this)->CopyInnerTo(it); \
   if (NS_FAILED(rv2)) {                                            \
     rv = rv2;                                                      \
   }                                                                \
   if (NS_SUCCEEDED(rv)) {                                          \
     it.forget(aResult);                                            \
   }                                                                \
   return rv;                                                       \
 }

#define NS_IMPL_ELEMENT_CLONE_WITH_INIT_AND_PARSER(_elementName) \
 NS_IMPL_ELEMENT_CLONE_WITH_INIT(_elementName, NOT_FROM_PARSER)

#endif  // mozilla_dom_Element_h__