dom/base/Element.h
author alwu <alwu@mozilla.com>
Thu, 09 May 2019 18:26:17 +0000
changeset 535196 2d810269b72e198765af3d997f3b117d832afd38
parent 534572 801ff1a58ffc0cbfa6641b31b7a030b53d5bc6d5
child 535197 1fa720d18b38e35831de185ac2f55356c88a7d21
permissions -rw-r--r--
Bug 1536762 - part1 : use unscaled bounding box'size as a cue box's size. r=baku,heycam When adjusting cue's position, the goal is to place cue boxes fully inside the rendering area, and place in the right place. In order to check whether the box is correctly inside the rendering area, we have to know the correct size of the cue box. Therefore, we implement the new chrome-only APIs to acquire this information (box's height and width), and this returned value won't be affected by CSS transformation, which is good for positioning. Differential Revision: https://phabricator.services.mozilla.com/D27178

/* -*- 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 "AttrArray.h"
#include "DOMIntersectionObserver.h"
#include "nsAttrValue.h"
#include "nsAttrValueInlines.h"
#include "nsChangeHint.h"
#include "nsContentUtils.h"
#include "nsDOMAttributeMap.h"
#include "nsILinkHandler.h"
#include "nsINodeList.h"
#include "nsIScrollableFrame.h"
#include "nsNodeUtils.h"
#include "nsPresContext.h"
#include "Units.h"
#include "mozilla/Attributes.h"
#include "mozilla/CORSMode.h"
#include "mozilla/EventForwards.h"
#include "mozilla/EventStates.h"
#include "mozilla/FlushType.h"
#include "mozilla/PresShell.h"
#include "mozilla/PseudoStyleType.h"
#include "mozilla/RustCell.h"
#include "mozilla/SMILAttr.h"
#include "mozilla/UniquePtr.h"
#include "mozilla/dom/Attr.h"
#include "mozilla/dom/BindingDeclarations.h"
#include "mozilla/dom/DirectionalityUtils.h"
#include "mozilla/dom/FragmentOrElement.h"
#include "mozilla/dom/DOMRect.h"
#include "mozilla/dom/DOMTokenListSupportedTokens.h"
#include "mozilla/dom/ElementBinding.h"
#include "mozilla/dom/Nullable.h"
#include "mozilla/dom/PointerEventHandler.h"
#include "mozilla/dom/WindowBinding.h"

class mozAutoDocUpdate;
class nsIFrame;
class nsIMozBrowserFrame;
class nsIURI;
class nsIScrollableFrame;
class nsAttrValueOrString;
class nsContentList;
class nsDOMTokenList;
struct nsRect;
class nsFocusManager;
class nsGlobalWindowInner;
class nsGlobalWindowOuter;
class nsDOMCSSAttributeDeclaration;
class nsDOMStringMap;
struct ServoNodeData;

class nsIDOMXULButtonElement;
class nsIDOMXULContainerElement;
class nsIDOMXULContainerItemElement;
class nsIDOMXULControlElement;
class nsIDOMXULMenuListElement;
class nsIDOMXULMultiSelectControlElement;
class nsIDOMXULRadioGroupElement;
class nsIDOMXULRelatedElement;
class nsIDOMXULSelectControlElement;
class nsIDOMXULSelectControlItemElement;
class nsIBrowser;
class nsIAutoCompletePopup;

namespace mozilla {
class DeclarationBlock;
struct MutationClosureData;
class TextEditor;
namespace css {
struct URLValue;
}  // namespace css
namespace dom {
struct AnimationFilter;
struct ScrollIntoViewOptions;
struct ScrollToOptions;
class DOMIntersectionObserver;
class DOMMatrixReadOnly;
class Element;
class ElementOrCSSPseudoElement;
class UnrestrictedDoubleOrKeyframeAnimationOptions;
enum class CallerType : uint32_t;
typedef nsDataHashtable<nsRefPtrHashKey<DOMIntersectionObserver>, int32_t>
    IntersectionObserverList;
}  // namespace dom
}  // namespace mozilla

// 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 {
  // 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),

  // Remaining bits are for subclasses
  ELEMENT_TYPE_SPECIFIC_BITS_OFFSET = NODE_TYPE_SPECIFIC_BITS_OFFSET + 4
};

#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;

namespace dom {

struct CustomElementDefinition;
class Animation;
class CustomElementRegistry;
class Link;
class DOMRect;
class DOMRectList;
class Flex;
class Grid;

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

class Element : public FragmentOrElement {
 public:
#ifdef MOZILLA_INTERNAL_API
  explicit Element(already_AddRefed<mozilla::dom::NodeInfo>&& aNodeInfo)
      : FragmentOrElement(std::move(aNodeInfo)),
        mState(NS_EVENT_STATE_MOZ_READONLY | NS_EVENT_STATE_DEFINED) {
    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_DECLARE_STATIC_IID_ACCESSOR(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 mozilla/EventStates.h
   * for the possible bits that could be set here.
   */
  EventStates State() const {
    // mState is maintained by having whoever might have changed it
    // call UpdateState() or one of the other mState mutators.
    return mState;
  }

  /**
   * Ask this element to update its state.  If aNotify is false, then
   * state change notifications will not be dispatched; in that
   * situation it is the caller's responsibility to dispatch them.
   *
   * In general, aNotify should only be false if we're guaranteed that
   * the element can't have a frame no matter what its style is
   * (e.g. if we're in the middle of adding it to the document or
   * removing it from the document).
   */
  void UpdateState(bool aNotify);

  /**
   * Method to update mState with link state information.  This does not notify.
   */
  void UpdateLinkState(EventStates aState);

  virtual int32_t TabIndexDefault() { return -1; }

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

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

  /**
   * Sets or unsets an XBL binding for this element. Setting a
   * binding on an element that already has a binding will remove the
   * old binding.
   *
   * @param aBinding The binding to bind to this content. If nullptr is
   *        provided as the argument, then existing binding will be
   *        removed.
   *
   * @param aOldBindingManager The old binding manager that contains
   *                           this content if this content was adopted
   *                           to another document.
   */
  void SetXBLBinding(nsXBLBinding* aBinding,
                     nsBindingManager* aOldBindingManager = nullptr);

  /**
   * 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);

  /**
   * Make focus on this element.
   */
  virtual void Focus(const FocusOptions& aOptions, ErrorResult& aError);

  /**
   * Show blur and clear focus.
   */
  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.
   */
  EventStates 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.
    EventStates mLocks;
    // mValues tracks if the locked state should be on or off.
    EventStates 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(EventStates aStates, bool aEnabled);

  /**
   * Remove a style state lock on this element.
   */
  void UnlockStyleStates(EventStates 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(NS_EVENT_STATE_DIR_ATTR_LIKE_AUTO);
  }

  /**
   * Elements with dir="rtl" or dir="ltr".
   */
  bool HasFixedDir() const {
    return State().HasAtLeastOneOfStates(NS_EVENT_STATE_DIR_ATTR_LTR |
                                         NS_EVENT_STATE_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.
   */
  const nsMappedAttributes* GetMappedAttributes() const;

  void ClearMappedServoStyle() { mAttrs.ClearMappedServoStyle(); }

  /**
   * 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.
   */
  nsresult SetSMILOverrideStyleDeclaration(DeclarationBlock* aDeclaration);

  /**
   * 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) {
    return nullptr;
  }

  /**
   * 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(bool aIgnoreTabindex) const;

  /**
   * Returns |this| as an nsIMozBrowserFrame* if the element is a frame or
   * iframe element.
   *
   * We have this method, rather than using QI, so that we can use it during
   * the servo traversal, where we can't QI DOM nodes because of non-thread-safe
   * refcounts.
   */
  virtual nsIMozBrowserFrame* GetAsMozBrowserFrame() { return nullptr; }

  /**
   * Is the attribute named stored in the mapped attributes?
   *
   * // XXXbz we use this method in HasAttributeDependentStyle, so svg
   *    returns true here even though it stores nothing in the mapped
   *    attributes.
   */
  NS_IMETHOD_(bool) IsAttributeMapped(const nsAtom* aAttribute) const;

  /**
   * 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,
                                              int32_t aModType) const;

  inline Directionality GetDirectionality() const {
    if (HasFlag(NODE_HAS_DIRECTION_RTL)) {
      return eDir_RTL;
    }

    if (HasFlag(NODE_HAS_DIRECTION_LTR)) {
      return eDir_LTR;
    }

    return eDir_NotSet;
  }

  inline void SetDirectionality(Directionality aDir, bool aNotify) {
    UnsetFlags(NODE_ALL_DIRECTION_FLAGS);
    if (!aNotify) {
      RemoveStatesSilently(DIRECTION_STATES);
    }

    switch (aDir) {
      case (eDir_RTL):
        SetFlags(NODE_HAS_DIRECTION_RTL);
        if (!aNotify) {
          AddStatesSilently(NS_EVENT_STATE_RTL);
        }
        break;

      case (eDir_LTR):
        SetFlags(NODE_HAS_DIRECTION_LTR);
        if (!aNotify) {
          AddStatesSilently(NS_EVENT_STATE_LTR);
        }
        break;

      default:
        break;
    }

    /*
     * Only call UpdateState if we need to notify, because we call
     * SetDirectionality for every element, and UpdateState is very very slow
     * for some elements.
     */
    if (aNotify) {
      UpdateState(true);
    }
  }

  bool GetBindingURL(Document* aDocument, css::URLValue** aResult);

  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);

  /**
   * 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.
   */
  inline 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(CustomElementData* aData);

  /**
   * 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.
   */
  void SetCustomElementDefinition(CustomElementDefinition* aDefinition);

  void SetDefined(bool aSet) {
    if (aSet) {
      AddStates(NS_EVENT_STATE_DEFINED);
    } else {
      RemoveStates(NS_EVENT_STATE_DEFINED);
    }
  }

 protected:
  /**
   * Method to get the _intrinsic_ content state of this element.  This is the
   * state that is independent of the element's presentation.  To get the full
   * content state, use State().  See mozilla/EventStates.h for
   * the possible bits that could be set here.
   */
  virtual EventStates IntrinsicState() const;

  /**
   * 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.
   */
  void AddStatesSilently(EventStates 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(EventStates aStates) { mState &= ~aStates; }

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

  MOZ_CAN_RUN_SCRIPT
  nsIScrollableFrame* GetScrollFrame(nsIFrame** aStyledFrame = nullptr,
                                     FlushType aFlushType = FlushType::Layout);

 private:
  // Need to allow the ESM, nsGlobalWindow, and the focus manager to
  // set our state
  friend class mozilla::EventStateManager;
  friend class ::nsGlobalWindowInner;
  friend class ::nsGlobalWindowOuter;
  friend class ::nsFocusManager;

  // Allow CusomtElementRegistry to call AddStates.
  friend class CustomElementRegistry;

  // Also need to allow Link to call UpdateLinkState.
  friend class Link;

  void NotifyStateChange(EventStates aStates);

  void NotifyStyleStateChange(EventStates aStates);

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

 protected:
  // Methods for the ESM, nsGlobalWindow and focus manager to manage state bits.
  // 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.
  virtual void AddStates(EventStates aStates) {
    MOZ_ASSERT(!aStates.HasAtLeastOneOfStates(INTRINSIC_STATES),
               "Should only be adding externally-managed states here");
    AddStatesSilently(aStates);
    NotifyStateChange(aStates);
  }
  virtual void RemoveStates(EventStates aStates) {
    MOZ_ASSERT(!aStates.HasAtLeastOneOfStates(INTRINSIC_STATES),
               "Should only be removing externally-managed states here");
    RemoveStatesSilently(aStates);
    NotifyStateChange(aStates);
  }
  virtual void ToggleStates(EventStates aStates, bool aNotify) {
    MOZ_ASSERT(!aStates.HasAtLeastOneOfStates(INTRINSIC_STATES),
               "Should only be removing externally-managed states here");
    mState ^= aStates;
    if (aNotify) {
      NotifyStateChange(aStates);
    }
  }

 public:
  // Public methods to manage state bits in MANUALLY_MANAGED_STATES.
  void AddManuallyManagedStates(EventStates aStates) {
    MOZ_ASSERT(MANUALLY_MANAGED_STATES.HasAllStates(aStates),
               "Should only be adding manually-managed states here");
    AddStates(aStates);
  }
  void RemoveManuallyManagedStates(EventStates aStates) {
    MOZ_ASSERT(MANUALLY_MANAGED_STATES.HasAllStates(aStates),
               "Should only be removing manually-managed states here");
    RemoveStates(aStates);
  }

  void UpdateEditableState(bool aNotify) override;

  nsresult BindToTree(Document* aDocument, nsIContent* aParent,
                      nsIContent* aBindingParent) override;

  void UnbindFromTree(bool aDeep = true, bool aNullParent = true) override;

  /**
   * 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 or there are mutation listeners that must be triggered, 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 and we don't
   * have mutation listeners (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 MutationEvent_Binding::MODIFICATION or to
   *   MutationEvent_Binding::ADDITION, but only if this helper returns true
   * @param aHasListeners [out] Set to true if there are mutation event
   *   listeners listening for NS_EVENT_BITS_MUTATION_ATTRMODIFIED
   * @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, uint8_t* aModType,
                             bool* aHasListeners, bool* aOldValueSet);

  /**
   * Notifies mutation listeners if aNotify is true, there are mutation
   * listeners, 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 MutationEvent_Binding::MODIFICATION or to
   *   MutationEvent_Binding::ADDITION, but only if this helper returns true
   * @param aHasListeners [out] Set to true if there are mutation event
   *   listeners listening for NS_EVENT_BITS_MUTATION_ATTRMODIFIED
   * @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, uint8_t* aModType,
                              bool* aHasListeners, bool* aOldValueSet);

  /**
   * Sets the class attribute to a value that contains no whitespace.
   * Assumes that we are not notifying and that the attribute hasn't been
   * set previously.
   */
  nsresult SetSingleClassFromParser(nsAtom* aSingleClassName);

  // 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 {
    return GetAttr(kNameSpaceID_None, aName, aResult);
  }

  /**
   * 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;

  bool HasAttr(const nsAtom* aAttr) const {
    return HasAttr(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;

  enum { ATTR_MISSING = -1, ATTR_VALUE_NO_MATCH = -2 };
  /**
   * 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
   */
  typedef nsStaticAtom* const AttrValuesArray;
  int32_t FindAttrValueIn(int32_t aNameSpaceID, const nsAtom* aName,
                          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);

  /**
   * Remove an attribute so that it is no longer explicitly specified.
   *
   * @param aNameSpaceID the namespace id of the attribute
   * @param aAttr 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* aAttribute, bool aNotify);

  /**
   * Get the namespace / name / prefix of a given attribute.
   *
   * @param   aIndex the index of the attribute name
   * @returns The name at the given index, or null if the index is
   *          out-of-bounds.
   * @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.
   */
  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);
  }

  /**
   * 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(); }

  virtual bool IsNodeOfType(uint32_t aFlags) const override;

  /**
   * 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 DEBUG
  virtual void List(FILE* out = stdout, int32_t aIndent = 0) const override {
    List(out, aIndent, EmptyCString());
  }
  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 short (preferably one line) string
   * describing the element.
   */
  void Describe(nsAString& aOutDescription) 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);
  }

  static nsStaticAtom* const* HTMLSVGPropertiesToTraverseAndUnlink();

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

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

 protected:
  inline bool GetAttr(int32_t aNameSpaceID, const nsAtom* aName,
                      DOMString& aResult) const {
    NS_ASSERTION(nullptr != aName, "must have attribute name");
    NS_ASSERTION(aNameSpaceID != kNameSpaceID_Unknown,
                 "must have a real namespace ID!");
    MOZ_ASSERT(aResult.IsEmpty(), "Should have empty string coming in");
    const nsAttrValue* val = mAttrs.GetAttr(aName, aNameSpaceID);
    if (val) {
      val->ToString(aResult);
      return true;
    }
    // else DOMString comes pre-emptied.
    return false;
  }

 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;
  }

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

  nsDOMTokenList* ClassList();
  nsDOMAttributeMap* Attributes() {
    nsDOMSlots* slots = DOMSlots();
    if (!slots->mAttributeMap) {
      slots->mAttributeMap = new nsDOMAttributeMap(this);
    }

    return slots->mAttributeMap;
  }

  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);
  }

  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 nsAString& aSelector, ErrorResult& aResult);
  bool Matches(const nsAString& 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);

  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);

 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) {
    bool activeState = false;
    if (nsContentUtils::ShouldResistFingerprinting(GetComposedDoc()) &&
        aPointerId != PointerEventHandler::GetSpoofedPointerIdForRFP()) {
      aError.Throw(NS_ERROR_DOM_INVALID_POINTER_ERR);
      return;
    }
    if (!PointerEventHandler::GetPointerInfo(aPointerId, activeState)) {
      aError.Throw(NS_ERROR_DOM_INVALID_POINTER_ERR);
      return;
    }
    if (!IsInComposedDoc()) {
      aError.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
      return;
    }
    if (OwnerDoc()->GetPointerLockElement()) {
      // Throw an exception 'InvalidStateError' while the page has a locked
      // element.
      aError.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
      return;
    }
    if (!activeState) {
      return;
    }
    PointerEventHandler::SetPointerCaptureById(aPointerId, this);
  }
  void ReleasePointerCapture(int32_t aPointerId, ErrorResult& aError) {
    bool activeState = false;
    if (nsContentUtils::ShouldResistFingerprinting(GetComposedDoc()) &&
        aPointerId != PointerEventHandler::GetSpoofedPointerIdForRFP()) {
      aError.Throw(NS_ERROR_DOM_INVALID_POINTER_ERR);
      return;
    }
    if (!PointerEventHandler::GetPointerInfo(aPointerId, activeState)) {
      aError.Throw(NS_ERROR_DOM_INVALID_POINTER_ERR);
      return;
    }
    if (HasPointerCapture(aPointerId)) {
      PointerEventHandler::ReleasePointerCaptureById(aPointerId);
    }
  }
  bool HasPointerCapture(long aPointerId) {
    PointerCaptureInfo* pointerCaptureInfo =
        PointerEventHandler::GetPointerCaptureInfo(aPointerId);
    if (pointerCaptureInfo && pointerCaptureInfo->mPendingContent == this) {
      return true;
    }
    return false;
  }
  void SetCapture(bool aRetargetToElement) {
    // If there is already an active capture, ignore this request. This would
    // occur if a splitter, frame resizer, etc had already captured and we don't
    // want to override those.
    if (!PresShell::GetCapturingContent()) {
      PresShell::SetCapturingContent(
          this, CaptureFlags::PreventDragStart |
                    (aRetargetToElement ? CaptureFlags::RetargetToElement
                                        : CaptureFlags::None));
    }
  }

  void SetCaptureAlways(bool aRetargetToElement) {
    PresShell::SetCapturingContent(
        this, CaptureFlags::PreventDragStart |
                  CaptureFlags::IgnoreAllowedState |
                  (aRetargetToElement ? CaptureFlags::RetargetToElement
                                      : CaptureFlags::None));
  }

  void ReleaseCapture() {
    if (PresShell::GetCapturingContent() == this) {
      PresShell::ReleaseCapturingContent();
    }
  }

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

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

  // Shadow DOM v1
  already_AddRefed<ShadowRoot> AttachShadow(const ShadowRootInit& aInit,
                                            ErrorResult& aError);
  bool CanAttachShadowDOM() const;

  already_AddRefed<ShadowRoot> AttachShadowWithoutNameChecks(
      ShadowRootMode aMode);

  // Attach UA Shadow Root if it is not attached.
  void AttachAndSetUAShadowRoot();

  // 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;
  }

 private:
  MOZ_CAN_RUN_SCRIPT void ScrollIntoView(const ScrollIntoViewOptions& aOptions);

 public:
  MOZ_CAN_RUN_SCRIPT
  void ScrollIntoView(const BooleanOrScrollIntoViewOptions& aObject);
  MOZ_CAN_RUN_SCRIPT void Scroll(double aXScroll, double aYScroll);
  MOZ_CAN_RUN_SCRIPT void Scroll(const ScrollToOptions& aOptions);
  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 int32_t ScrollTop();
  MOZ_CAN_RUN_SCRIPT void SetScrollTop(int32_t aScrollTop);
  MOZ_CAN_RUN_SCRIPT int32_t ScrollLeft();
  MOZ_CAN_RUN_SCRIPT void SetScrollLeft(int32_t 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 nsPresContext::AppUnitsToIntCSSPixels(GetClientAreaRect().y);
  }
  MOZ_CAN_RUN_SCRIPT int32_t ClientLeft() {
    return nsPresContext::AppUnitsToIntCSSPixels(GetClientAreaRect().x);
  }
  MOZ_CAN_RUN_SCRIPT int32_t ClientWidth() {
    return nsPresContext::AppUnitsToIntCSSPixels(GetClientAreaRect().Width());
  }
  MOZ_CAN_RUN_SCRIPT int32_t ClientHeight() {
    return nsPresContext::AppUnitsToIntCSSPixels(GetClientAreaRect().Height());
  }
  MOZ_CAN_RUN_SCRIPT int32_t ScrollTopMin() {
    nsIScrollableFrame* sf = GetScrollFrame();
    return sf ? nsPresContext::AppUnitsToIntCSSPixels(sf->GetScrollRange().y)
              : 0;
  }
  MOZ_CAN_RUN_SCRIPT int32_t ScrollTopMax() {
    nsIScrollableFrame* sf = GetScrollFrame();
    return sf ? nsPresContext::AppUnitsToIntCSSPixels(
                    sf->GetScrollRange().YMost())
              : 0;
  }
  MOZ_CAN_RUN_SCRIPT int32_t ScrollLeftMin() {
    nsIScrollableFrame* sf = GetScrollFrame();
    return sf ? nsPresContext::AppUnitsToIntCSSPixels(sf->GetScrollRange().x)
              : 0;
  }
  MOZ_CAN_RUN_SCRIPT int32_t ScrollLeftMax() {
    nsIScrollableFrame* sf = GetScrollFrame();
    return sf ? nsPresContext::AppUnitsToIntCSSPixels(
                    sf->GetScrollRange().XMost())
              : 0;
  }

  MOZ_CAN_RUN_SCRIPT double ClientHeightDouble() {
    return nsPresContext::AppUnitsToDoubleCSSPixels(
        GetClientAreaRect().Height());
  }

  MOZ_CAN_RUN_SCRIPT double ClientWidthDouble() {
    return nsPresContext::AppUnitsToDoubleCSSPixels(
        GetClientAreaRect().Width());
  }

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

  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);

  // A helper method that factors out the common functionality needed by
  // Element::Animate and CSSPseudoElement::Animate
  static already_AddRefed<Animation> Animate(
      const Nullable<ElementOrCSSPseudoElement>& aTarget, JSContext* aContext,
      JS::Handle<JSObject*> aKeyframes,
      const UnrestrictedDoubleOrKeyframeAnimationOptions& aOptions,
      ErrorResult& aError);

  // Note: GetAnimations will flush style while GetAnimationsUnsorted won't.
  // Callers must keep this element alive because flushing style may destroy
  // this element.
  void GetAnimations(const AnimationFilter& filter,
                     nsTArray<RefPtr<Animation>>& aAnimations);
  static void GetAnimationsUnsorted(Element* aElement,
                                    PseudoStyleType aPseudoType,
                                    nsTArray<RefPtr<Animation>>& aAnimations);

  virtual void GetInnerHTML(nsAString& aInnerHTML, OOMReporter& aError);
  virtual void SetInnerHTML(const nsAString& aInnerHTML,
                            nsIPrincipal* aSubjectPrincipal,
                            ErrorResult& aError);
  void GetOuterHTML(nsAString& aOuterHTML);
  void SetOuterHTML(const nsAString& aOuterHTML, ErrorResult& aError);
  void InsertAdjacentHTML(const nsAString& aPosition, const nsAString& aText,
                          ErrorResult& aError);

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

  /**
   * 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
   */
  nsresult 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);
  }

  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;
  }

  virtual 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);
  }

  /**
   * Called when we have been adopted, and the information of the
   * node has been changed.
   *
   * The new document can be reached via OwnerDoc().
   *
   * If you override this method,
   * please call up to the parent NodeInfoChanged.
   *
   * If you change this, change also the similar method in Link.
   */
  virtual void NodeInfoChanged(Document* aOldDoc) {}

  /**
   * 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);

  JSObject* WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) final;

  nsINode* GetScopeChainParent() const override;

  /**
   * Locate a TextEditor rooted at this content node, if there is one.
   */
  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(kNameSpaceID_None, 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);
  }

  /**
   * 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();

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

  /*
   * 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();

  void RegisterIntersectionObserver(DOMIntersectionObserver* aObserver);
  void UnregisterIntersectionObserver(DOMIntersectionObserver* aObserver);
  void UnlinkIntersectionObservers();
  bool UpdateIntersectionObservation(DOMIntersectionObserver* aObserver,
                                     int32_t threshold);

  // 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();

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

  /**
   * Set attribute and (if needed) notify documentobservers and fire off
   * mutation events.  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 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 aModType      MutationEvent_Binding::MODIFICATION or ADDITION.  Only
   *                      needed if aFireMutation or aNotify is true.
   * @param aFireMutation should mutation-events be fired?
   * @param aNotify       should we notify document-observers?
   * @param aCallAfterSetAttr should we call AfterSetAttr?
   * @param aComposedDocument The current composed document of the element.
   */
  nsresult SetAttrAndNotify(int32_t aNamespaceID, nsAtom* aName,
                            nsAtom* aPrefix, const nsAttrValue* aOldValue,
                            nsAttrValue& aParsedValue,
                            nsIPrincipal* aMaybeScriptedPrincipal,
                            uint8_t aModType, bool aFireMutation, bool aNotify,
                            bool aCallAfterSetAttr, Document* aComposedDocument,
                            const mozAutoDocUpdate& aGuard);

  /**
   * Scroll to a new position using behavior evaluated from CSS and
   * a CSSOM-View DOM method ScrollOptions dictionary.  The scrolling may
   * be performed asynchronously or synchronously depending on the resolved
   * scroll-behavior.
   *
   * @param aScroll       Destination of scroll, in CSS pixels
   * @param aOptions      Dictionary of options to be evaluated
   */
  MOZ_CAN_RUN_SCRIPT
  void Scroll(const CSSIntPoint& aScroll, const ScrollOptions& aOptions);

  /**
   * 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);

  /**
   * Try to set the attribute as a mapped attribute, if applicable.  This will
   * only be called for attributes that are in the null namespace and only on
   * attributes that returned true when passed to IsAttributeMapped.  The
   * caller will not try to set the attr in any other way if this method
   * returns true (the value of aRetval does not matter for that purpose).
   *
   * @param aName the name of the attribute
   * @param aValue the nsAttrValue to set. Will be swapped with the existing
   *               value of the attribute if the attribute already exists.
   * @param [out] aValueWasSet If the attribute was not set previously,
   *                           aValue will be swapped with an empty attribute
   *                           and aValueWasSet will be set to false. Otherwise,
   *                           aValueWasSet will be set to true and aValue will
   *                           contain the previous value set.
   * @param [out] aRetval the nsresult status of the operation, if any.
   * @return true if the setting was attempted, false otherwise.
   */
  virtual bool SetAndSwapMappedAttribute(nsAtom* aName, nsAttrValue& aValue,
                                         bool* aValueWasSet, nsresult* aRetval);

  /**
   * 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 nsresult BeforeSetAttr(int32_t aNamespaceID, nsAtom* aName,
                                 const nsAttrValueOrString* 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.
   */
  // Note that this is inlined so that when subclasses call it it gets
  // inlined.  Those calls don't go through a vtable.
  virtual nsresult AfterSetAttr(int32_t aNamespaceID, nsAtom* aName,
                                const nsAttrValue* aValue,
                                const nsAttrValue* aOldValue,
                                nsIPrincipal* aMaybeScriptedPrincipal,
                                bool aNotify) {
    return NS_OK;
  }

  /**
   * 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 nsAttrValueOrString* 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.
   */
  // Note that this is inlined so that when subclasses call it it gets
  // inlined.  Those calls don't go through a vtable.
  virtual nsresult 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
   * @param aURI the uri of the link, set only if the return value is true [OUT]
   * @return true if we can handle the link event, false otherwise
   */
  bool CheckHandleEventForLinksPrecondition(EventChainVisitor& aVisitor,
                                            nsIURI** aURI) const;

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

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

  /**
   * 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?)
   *
   * 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).
   */
  virtual void GetLinkTarget(nsAString& aTarget);

  nsDOMTokenList* GetTokenList(
      nsAtom* aAtom,
      const DOMTokenListSupportedTokenArray aSupportedTokens = nullptr);

  /**
   * Copy attributes and state to another element
   * @param aDest the object to copy to
   */
  nsresult CopyInnerTo(Element* aDest);

 private:
  /**
   * 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();

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

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

class RemoveFromBindingManagerRunnable : public mozilla::Runnable {
 public:
  RemoveFromBindingManagerRunnable(nsBindingManager* aManager,
                                   nsIContent* aContent, Document* aDoc);

  NS_IMETHOD Run() override;

 private:
  virtual ~RemoveFromBindingManagerRunnable();
  RefPtr<nsBindingManager> mManager;
  RefPtr<nsIContent> mContent;
  RefPtr<Document> mDoc;
};

NS_DEFINE_STATIC_IID_ACCESSOR(Element, NS_ELEMENT_IID)

inline bool Element::HasAttr(int32_t aNameSpaceID, const nsAtom* aName) const {
  NS_ASSERTION(nullptr != aName, "must have attribute name");
  NS_ASSERTION(aNameSpaceID != kNameSpaceID_Unknown,
               "must have a real namespace ID!");

  return mAttrs.IndexOfAttr(aName, aNameSpaceID) >= 0;
}

inline bool Element::AttrValueIs(int32_t aNameSpaceID, const nsAtom* aName,
                                 const nsAString& aValue,
                                 nsCaseTreatment aCaseSensitive) const {
  NS_ASSERTION(aName, "Must have attr name");
  NS_ASSERTION(aNameSpaceID != kNameSpaceID_Unknown, "Must have namespace");

  const nsAttrValue* val = mAttrs.GetAttr(aName, aNameSpaceID);
  return val && val->Equals(aValue, aCaseSensitive);
}

inline bool Element::AttrValueIs(int32_t aNameSpaceID, const nsAtom* aName,
                                 const nsAtom* aValue,
                                 nsCaseTreatment aCaseSensitive) const {
  NS_ASSERTION(aName, "Must have attr name");
  NS_ASSERTION(aNameSpaceID != kNameSpaceID_Unknown, "Must have namespace");
  NS_ASSERTION(aValue, "Null value atom");

  const nsAttrValue* val = mAttrs.GetAttr(aName, aNameSpaceID);
  return val && val->Equals(aValue, aCaseSensitive);
}

}  // namespace dom
}  // namespace mozilla

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::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<mozilla::dom::NodeInfo> ni(aNodeInfo);                   \
    RefPtr<_elementName> it = new _elementName(ni.forget());        \
    nsresult rv = const_cast<_elementName*>(this)->CopyInnerTo(it); \
    if (NS_SUCCEEDED(rv)) {                                         \
      it.forget(aResult);                                           \
    }                                                               \
                                                                    \
    return rv;                                                      \
  }

#define EXPAND(...) __VA_ARGS__
#define NS_IMPL_ELEMENT_CLONE_WITH_INIT_HELPER(_elementName, extra_args_) \
  nsresult _elementName::Clone(mozilla::dom::NodeInfo* aNodeInfo,         \
                               nsINode** aResult) const {                 \
    *aResult = nullptr;                                                   \
    RefPtr<mozilla::dom::NodeInfo> ni(aNodeInfo);                         \
    RefPtr<_elementName> it =                                             \
        new _elementName(ni.forget() EXPAND extra_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(_elementName) \
  NS_IMPL_ELEMENT_CLONE_WITH_INIT_HELPER(_elementName, ())
#define NS_IMPL_ELEMENT_CLONE_WITH_INIT_AND_PARSER(_elementName) \
  NS_IMPL_ELEMENT_CLONE_WITH_INIT_HELPER(_elementName, (, NOT_FROM_PARSER))

#endif  // mozilla_dom_Element_h__