/*
 * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
 *           (C) 1999 Antti Koivisto (koivisto@kde.org)
 *           (C) 2001 Peter Kelly (pmk@post.com)
 *           (C) 2001 Dirk Mueller (mueller@kde.org)
 * Copyright (C) 2003-2011, 2013, 2014 Apple Inc. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 *
 */

#ifndef Element_h
#define Element_h

#include "core/CSSPropertyNames.h"
#include "core/CoreExport.h"
#include "core/HTMLNames.h"
#include "core/css/CSSPrimitiveValue.h"
#include "core/css/CSSSelector.h"
#include "core/dom/AXObjectCache.h"
#include "core/dom/Attribute.h"
#include "core/dom/ContainerNode.h"
#include "core/dom/Document.h"
#include "core/dom/ElementData.h"
#include "core/dom/SpaceSplitString.h"
#include "core/html/CollectionType.h"
#include "platform/heap/Handle.h"
#include "platform/scroll/ScrollTypes.h"
#include "public/platform/WebFocusType.h"

namespace blink {

class ElementAnimations;
class Attr;
class Attribute;
class CSSStyleDeclaration;
class ClientRect;
class ClientRectList;
class CompositorMutation;
class CustomElementDefinition;
class DOMStringMap;
class DOMTokenList;
class ElementRareData;
class ElementShadow;
class ExceptionState;
class Image;
class InputDeviceCapabilities;
class Locale;
class MutableStylePropertySet;
class NamedNodeMap;
class ElementIntersectionObserverData;
class PseudoElement;
class ResizeObservation;
class ResizeObserver;
class ScrollState;
class ScrollStateCallback;
class ScrollToOptions;
class ShadowRoot;
class ShadowRootInit;
class StylePropertySet;
class StylePropertyMap;
class V0CustomElementDefinition;

enum SpellcheckAttributeState {
  SpellcheckAttributeTrue,
  SpellcheckAttributeFalse,
  SpellcheckAttributeDefault
};

enum ElementFlags {
  TabIndexWasSetExplicitly = 1 << 0,
  StyleAffectedByEmpty = 1 << 1,
  IsInCanvasSubtree = 1 << 2,
  ContainsFullScreenElement = 1 << 3,
  IsInTopLayer = 1 << 4,
  HasPendingResources = 1 << 5,
  AlreadySpellChecked = 1 << 6,

  NumberOfElementFlags =
      7,  // Required size of bitfield used to store the flags.
};

enum class ShadowRootType;

enum class SelectionBehaviorOnFocus {
  Reset,
  Restore,
  None,
};

struct FocusParams {
  STACK_ALLOCATED();

  FocusParams() {}
  FocusParams(SelectionBehaviorOnFocus selection,
              WebFocusType focusType,
              InputDeviceCapabilities* capabilities)
      : selectionBehavior(selection),
        type(focusType),
        sourceCapabilities(capabilities) {}

  SelectionBehaviorOnFocus selectionBehavior =
      SelectionBehaviorOnFocus::Restore;
  WebFocusType type = WebFocusTypeNone;
  Member<InputDeviceCapabilities> sourceCapabilities = nullptr;
};

typedef HeapVector<Member<Attr>> AttrNodeList;

class CORE_EXPORT Element : public ContainerNode {
  DEFINE_WRAPPERTYPEINFO();

 public:
  static Element* create(const QualifiedName&, Document*);
  ~Element() override;

  DEFINE_ATTRIBUTE_EVENT_LISTENER(beforecopy);
  DEFINE_ATTRIBUTE_EVENT_LISTENER(beforecut);
  DEFINE_ATTRIBUTE_EVENT_LISTENER(beforepaste);
  DEFINE_ATTRIBUTE_EVENT_LISTENER(copy);
  DEFINE_ATTRIBUTE_EVENT_LISTENER(cut);
  DEFINE_ATTRIBUTE_EVENT_LISTENER(gotpointercapture);
  DEFINE_ATTRIBUTE_EVENT_LISTENER(lostpointercapture);
  DEFINE_ATTRIBUTE_EVENT_LISTENER(paste);
  DEFINE_ATTRIBUTE_EVENT_LISTENER(search);
  DEFINE_ATTRIBUTE_EVENT_LISTENER(selectstart);
  DEFINE_ATTRIBUTE_EVENT_LISTENER(wheel);

  bool hasAttribute(const QualifiedName&) const;
  const AtomicString& getAttribute(const QualifiedName&) const;

  // Passing nullAtom as the second parameter removes the attribute when calling
  // either of these set methods.
  void setAttribute(const QualifiedName&, const AtomicString& value);
  void setSynchronizedLazyAttribute(const QualifiedName&,
                                    const AtomicString& value);

  void removeAttribute(const QualifiedName&);

  // Typed getters and setters for language bindings.
  int getIntegralAttribute(const QualifiedName& attributeName) const;
  void setIntegralAttribute(const QualifiedName& attributeName, int value);
  void setUnsignedIntegralAttribute(const QualifiedName& attributeName,
                                    unsigned value);
  double getFloatingPointAttribute(
      const QualifiedName& attributeName,
      double fallbackValue = std::numeric_limits<double>::quiet_NaN()) const;
  void setFloatingPointAttribute(const QualifiedName& attributeName,
                                 double value);

  // Call this to get the value of an attribute that is known not to be the
  // style attribute or one of the SVG animatable attributes.
  bool fastHasAttribute(const QualifiedName&) const;
  const AtomicString& fastGetAttribute(const QualifiedName&) const;
#if DCHECK_IS_ON()
  bool fastAttributeLookupAllowed(const QualifiedName&) const;
#endif

#ifdef DUMP_NODE_STATISTICS
  bool hasNamedNodeMap() const;
#endif
  bool hasAttributes() const;

  bool hasAttribute(const AtomicString& name) const;
  bool hasAttributeNS(const AtomicString& namespaceURI,
                      const AtomicString& localName) const;

  const AtomicString& getAttribute(const AtomicString& name) const;
  const AtomicString& getAttributeNS(const AtomicString& namespaceURI,
                                     const AtomicString& localName) const;

  void setAttribute(const AtomicString& name,
                    const AtomicString& value,
                    ExceptionState&);
  static bool parseAttributeName(QualifiedName&,
                                 const AtomicString& namespaceURI,
                                 const AtomicString& qualifiedName,
                                 ExceptionState&);
  void setAttributeNS(const AtomicString& namespaceURI,
                      const AtomicString& qualifiedName,
                      const AtomicString& value,
                      ExceptionState&);

  const AtomicString& getIdAttribute() const;
  void setIdAttribute(const AtomicString&);

  const AtomicString& getNameAttribute() const;
  const AtomicString& getClassAttribute() const;

  bool shouldIgnoreAttributeCase() const;

  // Call this to get the value of the id attribute for style resolution
  // purposes.  The value will already be lowercased if the document is in
  // compatibility mode, so this function is not suitable for non-style uses.
  const AtomicString& idForStyleResolution() const;

  // This getter takes care of synchronizing all attributes before returning the
  // AttributeCollection. If the Element has no attributes, an empty
  // AttributeCollection will be returned. This is not a trivial getter and its
  // return value should be cached for performance.
  AttributeCollection attributes() const;
  // This variant will not update the potentially invalid attributes. To be used
  // when not interested in style attribute or one of the SVG animation
  // attributes.
  AttributeCollection attributesWithoutUpdate() const;

  void scrollIntoView(bool alignToTop = true);
  void scrollIntoViewIfNeeded(bool centerIfNeeded = true);

  int offsetLeft();
  int offsetTop();
  int offsetWidth();
  int offsetHeight();

  Element* offsetParent();
  int clientLeft();
  int clientTop();
  int clientWidth();
  int clientHeight();
  double scrollLeft();
  double scrollTop();
  void setScrollLeft(double);
  void setScrollTop(double);
  int scrollWidth();
  int scrollHeight();

  void scrollBy(double x, double y);
  virtual void scrollBy(const ScrollToOptions&);
  void scrollTo(double x, double y);
  virtual void scrollTo(const ScrollToOptions&);

  IntRect boundsInViewport() const;
  // Returns an intersection rectangle of the bounds rectangle and the
  // viewport rectangle, in the visual viewport coordinate. This function is
  // used to show popups beside this element.
  IntRect visibleBoundsInVisualViewport() const;

  ClientRectList* getClientRects();
  ClientRect* getBoundingClientRect();

  bool hasNonEmptyLayoutSize() const;

  const AtomicString& computedRole();
  String computedName();

  void didMoveToNewDocument(Document&) override;

  void removeAttribute(const AtomicString& name);
  void removeAttributeNS(const AtomicString& namespaceURI,
                         const AtomicString& localName);

  Attr* detachAttribute(size_t index);

  Attr* getAttributeNode(const AtomicString& name);
  Attr* getAttributeNodeNS(const AtomicString& namespaceURI,
                           const AtomicString& localName);
  Attr* setAttributeNode(Attr*, ExceptionState&);
  Attr* setAttributeNodeNS(Attr*, ExceptionState&);
  Attr* removeAttributeNode(Attr*, ExceptionState&);

  Attr* attrIfExists(const QualifiedName&);
  Attr* ensureAttr(const QualifiedName&);

  AttrNodeList* attrNodeList();

  CSSStyleDeclaration* style();
  StylePropertyMap* styleMap();

  const QualifiedName& tagQName() const { return m_tagName; }
  String tagName() const { return nodeName(); }

  bool hasTagName(const QualifiedName& tagName) const {
    return m_tagName.matches(tagName);
  }
  bool hasTagName(const HTMLQualifiedName& tagName) const {
    return ContainerNode::hasTagName(tagName);
  }
  bool hasTagName(const SVGQualifiedName& tagName) const {
    return ContainerNode::hasTagName(tagName);
  }

  // Should be called only by Document::createElementNS to fix up m_tagName
  // immediately after construction.
  void setTagNameForCreateElementNS(const QualifiedName&);

  // A fast function for checking the local name against another atomic string.
  bool hasLocalName(const AtomicString& other) const {
    return m_tagName.localName() == other;
  }

  const AtomicString& localName() const { return m_tagName.localName(); }
  AtomicString localNameForSelectorMatching() const;
  const AtomicString& prefix() const { return m_tagName.prefix(); }
  const AtomicString& namespaceURI() const { return m_tagName.namespaceURI(); }

  const AtomicString& locateNamespacePrefix(
      const AtomicString& namespaceURI) const;

  String nodeName() const override;

  Element* cloneElementWithChildren();
  Element* cloneElementWithoutChildren();

  void setBooleanAttribute(const QualifiedName&, bool);

  virtual const StylePropertySet* additionalPresentationAttributeStyle() {
    return nullptr;
  }
  void invalidateStyleAttribute();

  const StylePropertySet* inlineStyle() const {
    return elementData() ? elementData()->m_inlineStyle.get() : nullptr;
  }

  void setInlineStyleProperty(CSSPropertyID,
                              CSSValueID identifier,
                              bool important = false);
  void setInlineStyleProperty(CSSPropertyID,
                              double value,
                              CSSPrimitiveValue::UnitType,
                              bool important = false);
  // TODO(sashab): Make this take a const CSSValue&.
  void setInlineStyleProperty(CSSPropertyID,
                              const CSSValue*,
                              bool important = false);
  bool setInlineStyleProperty(CSSPropertyID,
                              const String& value,
                              bool important = false);

  bool removeInlineStyleProperty(CSSPropertyID);
  void removeAllInlineStyleProperties();

  void synchronizeStyleAttributeInternal() const;

  const StylePropertySet* presentationAttributeStyle();
  virtual bool isPresentationAttribute(const QualifiedName&) const {
    return false;
  }
  virtual void collectStyleForPresentationAttribute(const QualifiedName&,
                                                    const AtomicString&,
                                                    MutableStylePropertySet*) {}

  // For exposing to DOM only.
  NamedNodeMap* attributesForBindings() const;

  enum class AttributeModificationReason { kDirectly, kByParser, kByCloning };
  struct AttributeModificationParams {
    STACK_ALLOCATED();
    AttributeModificationParams(const QualifiedName& qname,
                                const AtomicString& oldValue,
                                const AtomicString& newValue,
                                AttributeModificationReason reason)
        : name(qname), oldValue(oldValue), newValue(newValue), reason(reason) {}

    const QualifiedName& name;
    const AtomicString& oldValue;
    const AtomicString& newValue;
    const AttributeModificationReason reason;
  };

  // |attributeChanged| is called whenever an attribute is added, changed or
  // removed. It handles very common attributes such as id, class, name, style,
  // and slot.
  //
  // While the owner document is parsed, this function is called after all
  // attributes in a start tag were added to the element.
  virtual void attributeChanged(const AttributeModificationParams&);

  // |parseAttribute| is called by |attributeChanged|. If an element
  // implementation needs to check an attribute update, override this function.
  //
  // While the owner document is parsed, this function is called after all
  // attributes in a start tag were added to the element.
  virtual void parseAttribute(const AttributeModificationParams&);

  virtual bool hasLegalLinkAttribute(const QualifiedName&) const;
  virtual const QualifiedName& subResourceAttributeName() const;

  // Only called by the parser immediately after element construction.
  void parserSetAttributes(const Vector<Attribute>&);

  // Remove attributes that might introduce scripting from the vector leaving
  // the element unchanged.
  void stripScriptingAttributes(Vector<Attribute>&) const;

  bool sharesSameElementData(const Element& other) const {
    return elementData() == other.elementData();
  }

  // Clones attributes only.
  void cloneAttributesFromElement(const Element&);

  // Clones all attribute-derived data, including subclass specifics (through
  // copyNonAttributeProperties.)
  void cloneDataFromElement(const Element&);

  bool hasEquivalentAttributes(const Element* other) const;

  virtual void copyNonAttributePropertiesFromElement(const Element&) {}

  void attachLayoutTree(const AttachContext& = AttachContext()) override;
  void detachLayoutTree(const AttachContext& = AttachContext()) override;

  virtual LayoutObject* createLayoutObject(const ComputedStyle&);
  virtual bool layoutObjectIsNeeded(const ComputedStyle&);
  void recalcStyle(StyleRecalcChange, Text* nextTextSibling = nullptr);
  StyleRecalcChange rebuildLayoutTree();
  void pseudoStateChanged(CSSSelector::PseudoType);
  void setAnimationStyleChange(bool);
  void clearAnimationStyleChange();
  void setNeedsAnimationStyleRecalc();

  void setNeedsCompositingUpdate();

  bool supportsStyleSharing() const;

  ElementShadow* shadow() const;
  ElementShadow& ensureShadow();
  // If type of ShadowRoot (either closed or open) is explicitly specified,
  // creation of multiple shadow roots is prohibited in any combination and
  // throws an exception.  Multiple shadow roots are allowed only when
  // createShadowRoot() is used without any parameters from JavaScript.
  ShadowRoot* createShadowRoot(const ScriptState*, ExceptionState&);
  ShadowRoot* attachShadow(const ScriptState*,
                           const ShadowRootInit&,
                           ExceptionState&);
  ShadowRoot* createShadowRootInternal(ShadowRootType, ExceptionState&);

  ShadowRoot* openShadowRoot() const;
  ShadowRoot* closedShadowRoot() const;
  ShadowRoot* authorShadowRoot() const;
  ShadowRoot* userAgentShadowRoot() const;

  ShadowRoot* youngestShadowRoot() const;

  ShadowRoot* shadowRootIfV1() const;

  ShadowRoot& ensureUserAgentShadowRoot();

  bool isInDescendantTreeOf(const Element* shadowHost) const;

  // Returns the Element’s ComputedStyle. If the ComputedStyle is not already
  // stored on the Element, computes the ComputedStyle and stores it on the
  // Element’s ElementRareData.  Used for getComputedStyle when Element is
  // display none.
  const ComputedStyle* ensureComputedStyle(PseudoId = PseudoIdNone);

  // Methods for indicating the style is affected by dynamic updates (e.g.,
  // children changing, our position changing in our sibling list, etc.)
  bool styleAffectedByEmpty() const {
    return hasElementFlag(StyleAffectedByEmpty);
  }
  void setStyleAffectedByEmpty() { setElementFlag(StyleAffectedByEmpty); }

  void setIsInCanvasSubtree(bool value) {
    setElementFlag(IsInCanvasSubtree, value);
  }
  bool isInCanvasSubtree() const { return hasElementFlag(IsInCanvasSubtree); }

  bool isDefined() const {
    return !(static_cast<int>(getCustomElementState()) &
             static_cast<int>(CustomElementState::NotDefinedFlag));
  }
  bool isUpgradedV0CustomElement() {
    return getV0CustomElementState() == V0Upgraded;
  }
  bool isUnresolvedV0CustomElement() {
    return getV0CustomElementState() == V0WaitingForUpgrade;
  }

  AtomicString computeInheritedLanguage() const;
  Locale& locale() const;

  virtual void accessKeyAction(bool /*sendToAnyEvent*/) {}

  virtual bool isURLAttribute(const Attribute&) const { return false; }
  virtual bool isHTMLContentAttribute(const Attribute&) const { return false; }
  bool isJavaScriptURLAttribute(const Attribute&) const;
  virtual bool isSVGAnimationAttributeSettingJavaScriptURL(
      const Attribute&) const {
    return false;
  }
  bool isScriptingAttribute(const Attribute&) const;

  virtual bool isLiveLink() const { return false; }
  KURL hrefURL() const;

  KURL getURLAttribute(const QualifiedName&) const;
  KURL getNonEmptyURLAttribute(const QualifiedName&) const;

  virtual const AtomicString imageSourceURL() const;
  virtual Image* imageContents() { return nullptr; }

  virtual void focus(const FocusParams& = FocusParams());
  virtual void updateFocusAppearance(SelectionBehaviorOnFocus);
  virtual void blur();

  void setDistributeScroll(ScrollStateCallback*, String nativeScrollBehavior);
  void nativeDistributeScroll(ScrollState&);
  void setApplyScroll(ScrollStateCallback*, String nativeScrollBehavior);
  void removeApplyScroll();
  void nativeApplyScroll(ScrollState&);

  void callDistributeScroll(ScrollState&);
  void callApplyScroll(ScrollState&);

  ScrollStateCallback* getApplyScroll();

  // Whether this element can receive focus at all. Most elements are not
  // focusable but some elements, such as form controls and links, are. Unlike
  // layoutObjectIsFocusable(), this method may be called when layout is not up
  // to date, so it must not use the layoutObject to determine focusability.
  virtual bool supportsFocus() const;
  // isFocusable(), isKeyboardFocusable(), and isMouseFocusable() check
  // whether the element can actually be focused. Callers should ensure
  // ComputedStyle is up to date;
  // e.g. by calling Document::updateLayoutTreeIgnorePendingStylesheets().
  bool isFocusable() const;
  virtual bool isKeyboardFocusable() const;
  virtual bool isMouseFocusable() const;
  bool isFocusedElementInDocument() const;
  Element* adjustedFocusedElementInTreeScope() const;

  virtual void dispatchFocusEvent(
      Element* oldFocusedElement,
      WebFocusType,
      InputDeviceCapabilities* sourceCapabilities = nullptr);
  virtual void dispatchBlurEvent(
      Element* newFocusedElement,
      WebFocusType,
      InputDeviceCapabilities* sourceCapabilities = nullptr);
  virtual void dispatchFocusInEvent(
      const AtomicString& eventType,
      Element* oldFocusedElement,
      WebFocusType,
      InputDeviceCapabilities* sourceCapabilities = nullptr);
  void dispatchFocusOutEvent(
      const AtomicString& eventType,
      Element* newFocusedElement,
      InputDeviceCapabilities* sourceCapabilities = nullptr);

  virtual String innerText();
  String outerText();
  String innerHTML() const;
  String outerHTML() const;
  void setInnerHTML(const String&, ExceptionState& = ASSERT_NO_EXCEPTION);
  void setOuterHTML(const String&, ExceptionState&);

  Element* insertAdjacentElement(const String& where,
                                 Element* newChild,
                                 ExceptionState&);
  void insertAdjacentText(const String& where,
                          const String& text,
                          ExceptionState&);
  void insertAdjacentHTML(const String& where,
                          const String& html,
                          ExceptionState&);

  void setPointerCapture(int pointerId, ExceptionState&);
  void releasePointerCapture(int pointerId, ExceptionState&);

  // Returns true iff the element would capture the next pointer event. This
  // is true between a setPointerCapture call and a releasePointerCapture (or
  // implicit release) call:
  // https://w3c.github.io/pointerevents/#dom-element-haspointercapture
  bool hasPointerCapture(int pointerId) const;

  // Returns true iff the element has received a gotpointercapture event for
  // the |pointerId| but hasn't yet received a lostpointercapture event for
  // the same id. The time window during which this is true is "delayed" from
  // (but overlapping with) the time window for hasPointerCapture():
  // https://w3c.github.io/pointerevents/#process-pending-pointer-capture
  bool hasProcessedPointerCapture(int pointerId) const;

  String textFromChildren();

  virtual String title() const { return String(); }
  virtual String defaultToolTip() const { return String(); }

  virtual const AtomicString& shadowPseudoId() const;
  // The specified string must start with "-webkit-" or "-internal-". The
  // former can be used as a selector in any places, and the latter can be
  // used only in UA stylesheet.
  void setShadowPseudoId(const AtomicString&);

  LayoutSize minimumSizeForResizing() const;
  void setMinimumSizeForResizing(const LayoutSize&);

  // Called by the parser when this element's close tag is reached, signaling
  // that all child tags have been parsed and added.  This is needed for
  // <applet> and <object> elements, which can't lay themselves out until they
  // know all of their nested <param>s. [Radar 3603191, 4040848].  Also used for
  // script elements and some SVG elements for similar purposes, but making
  // parsing a special case in this respect should be avoided if possible.
  virtual void finishParsingChildren();

  void beginParsingChildren() { setIsFinishedParsingChildren(false); }

  PseudoElement* pseudoElement(PseudoId) const;
  LayoutObject* pseudoElementLayoutObject(PseudoId) const;

  virtual bool matchesDefaultPseudoClass() const { return false; }
  virtual bool matchesEnabledPseudoClass() const { return false; }
  virtual bool matchesReadOnlyPseudoClass() const { return false; }
  virtual bool matchesReadWritePseudoClass() const { return false; }
  virtual bool matchesValidityPseudoClasses() const { return false; }
  bool matches(const String& selectors, ExceptionState&);
  Element* closest(const String& selectors, ExceptionState&);
  virtual bool shouldAppearIndeterminate() const { return false; }

  DOMTokenList& classList();

  DOMStringMap& dataset();

  virtual bool isDateTimeEditElement() const { return false; }
  virtual bool isDateTimeFieldElement() const { return false; }
  virtual bool isPickerIndicatorElement() const { return false; }

  virtual bool isFormControlElement() const { return false; }
  virtual bool isSpinButtonElement() const { return false; }
  virtual bool isTextControl() const { return false; }
  virtual bool isOptionalFormControl() const { return false; }
  virtual bool isRequiredFormControl() const { return false; }
  virtual bool willValidate() const { return false; }
  virtual bool isValidElement() { return false; }
  virtual bool isInRange() const { return false; }
  virtual bool isOutOfRange() const { return false; }
  virtual bool isClearButtonElement() const { return false; }

  bool canContainRangeEndPoint() const override { return true; }

  // Used for disabled form elements; if true, prevents mouse events from being
  // dispatched to event listeners, and prevents DOMActivate events from being
  // sent at all.
  virtual bool isDisabledFormControl() const { return false; }

  bool hasPendingResources() const {
    return hasElementFlag(HasPendingResources);
  }
  void setHasPendingResources() { setElementFlag(HasPendingResources); }
  void clearHasPendingResources() { clearElementFlag(HasPendingResources); }
  virtual void buildPendingResource() {}

  bool isAlreadySpellChecked() const {
    return hasElementFlag(AlreadySpellChecked);
  }
  void setAlreadySpellChecked(bool value) {
    setElementFlag(AlreadySpellChecked, value);
  }

  void v0SetCustomElementDefinition(V0CustomElementDefinition*);
  V0CustomElementDefinition* v0CustomElementDefinition() const;

  void setCustomElementDefinition(CustomElementDefinition*);
  CustomElementDefinition* customElementDefinition() const;

  bool containsFullScreenElement() const {
    return hasElementFlag(ContainsFullScreenElement);
  }
  void setContainsFullScreenElement(bool);
  void setContainsFullScreenElementOnAncestorsCrossingFrameBoundaries(bool);

  bool isInTopLayer() const { return hasElementFlag(IsInTopLayer); }
  void setIsInTopLayer(bool);

  void requestPointerLock();

  bool isSpellCheckingEnabled() const;

  // FIXME: public for LayoutTreeBuilder, we shouldn't expose this though.
  PassRefPtr<ComputedStyle> styleForLayoutObject();

  bool hasID() const;
  bool hasClass() const;
  const SpaceSplitString& classNames() const;

  ScrollOffset savedLayerScrollOffset() const;
  void setSavedLayerScrollOffset(const ScrollOffset&);

  ElementAnimations* elementAnimations() const;
  ElementAnimations& ensureElementAnimations();
  bool hasAnimations() const;

  void synchronizeAttribute(const AtomicString& localName) const;

  MutableStylePropertySet& ensureMutableInlineStyle();
  void clearMutableInlineStyleIfEmpty();

  void setTabIndex(int);
  int tabIndex() const override;

  // A compositor proxy is a very limited wrapper around an element. It
  // exposes only those properties that are requested at the time the proxy is
  // created. In order to know which properties are actually proxied, we
  // maintain a count of the number of compositor proxies associated with each
  // property.
  bool hasCompositorProxy() const;
  void incrementCompositorProxiedProperties(uint32_t mutableProperties);
  void decrementCompositorProxiedProperties(uint32_t mutableProperties);
  uint32_t compositorMutableProperties() const;
  void updateFromCompositorMutation(const CompositorMutation&);

  // Helpers for V8DOMActivityLogger::logEvent.  They call logEvent only if
  // the element is isConnected() and the context is an isolated world.
  void logAddElementIfIsolatedWorldAndInDocument(const char element[],
                                                 const QualifiedName& attr1);
  void logAddElementIfIsolatedWorldAndInDocument(const char element[],
                                                 const QualifiedName& attr1,
                                                 const QualifiedName& attr2);
  void logAddElementIfIsolatedWorldAndInDocument(const char element[],
                                                 const QualifiedName& attr1,
                                                 const QualifiedName& attr2,
                                                 const QualifiedName& attr3);
  void logUpdateAttributeIfIsolatedWorldAndInDocument(
      const char element[],
      const AttributeModificationParams&);

  DECLARE_VIRTUAL_TRACE();

  DECLARE_VIRTUAL_TRACE_WRAPPERS();

  SpellcheckAttributeState spellcheckAttributeState() const;

  ElementIntersectionObserverData* intersectionObserverData() const;
  ElementIntersectionObserverData& ensureIntersectionObserverData();

  HeapHashMap<Member<ResizeObserver>, Member<ResizeObservation>>*
  resizeObserverData() const;
  HeapHashMap<Member<ResizeObserver>, Member<ResizeObservation>>&
  ensureResizeObserverData();
  void setNeedsResizeObserverUpdate();

 protected:
  Element(const QualifiedName& tagName, Document*, ConstructionType);

  const ElementData* elementData() const { return m_elementData.get(); }
  UniqueElementData& ensureUniqueElementData();

  void addPropertyToPresentationAttributeStyle(MutableStylePropertySet*,
                                               CSSPropertyID,
                                               CSSValueID identifier);
  void addPropertyToPresentationAttributeStyle(MutableStylePropertySet*,
                                               CSSPropertyID,
                                               double value,
                                               CSSPrimitiveValue::UnitType);
  void addPropertyToPresentationAttributeStyle(MutableStylePropertySet*,
                                               CSSPropertyID,
                                               const String& value);
  // TODO(sashab): Make this take a const CSSValue&.
  void addPropertyToPresentationAttributeStyle(MutableStylePropertySet*,
                                               CSSPropertyID,
                                               const CSSValue*);

  InsertionNotificationRequest insertedInto(ContainerNode*) override;
  void removedFrom(ContainerNode*) override;
  void childrenChanged(const ChildrenChange&) override;

  virtual void willRecalcStyle(StyleRecalcChange);
  virtual void didRecalcStyle(StyleRecalcChange);
  virtual PassRefPtr<ComputedStyle> customStyleForLayoutObject();

  virtual bool shouldRegisterAsNamedItem() const { return false; }
  virtual bool shouldRegisterAsExtraNamedItem() const { return false; }

  bool supportsSpatialNavigationFocus() const;

  void clearTabIndexExplicitlyIfNeeded();
  void setTabIndexExplicitly();
  // Subclasses may override this method to affect focusability. This method
  // must be called on an up-to-date ComputedStyle, so it may use existence of
  // layoutObject and the LayoutObject::style() to reason about focusability.
  // However, it must not retrieve layout information like position and size.
  // This method cannot be moved to LayoutObject because some focusable nodes
  // don't have layoutObjects. e.g., HTMLOptionElement.
  // TODO(tkent): Rename this to isFocusableStyle.
  virtual bool layoutObjectIsFocusable() const;

  // classAttributeChanged() exists to share code between
  // parseAttribute (called via setAttribute()) and
  // svgAttributeChanged (called when element.className.baseValue is set)
  void classAttributeChanged(const AtomicString& newClassString);

  static bool attributeValueIsJavaScriptURL(const Attribute&);

  PassRefPtr<ComputedStyle> originalStyleForLayoutObject();

  Node* insertAdjacent(const String& where, Node* newChild, ExceptionState&);

  virtual void parserDidSetAttributes() {}

 private:
  void scrollLayoutBoxBy(const ScrollToOptions&);
  void scrollLayoutBoxTo(const ScrollToOptions&);
  void scrollFrameBy(const ScrollToOptions&);
  void scrollFrameTo(const ScrollToOptions&);

  bool hasElementFlag(ElementFlags mask) const {
    return hasRareData() && hasElementFlagInternal(mask);
  }
  void setElementFlag(ElementFlags, bool value = true);
  void clearElementFlag(ElementFlags);
  bool hasElementFlagInternal(ElementFlags) const;

  bool isElementNode() const =
      delete;  // This will catch anyone doing an unnecessary check.
  bool isDocumentFragment() const =
      delete;  // This will catch anyone doing an unnecessary check.
  bool isDocumentNode() const =
      delete;  // This will catch anyone doing an unnecessary check.

  void styleAttributeChanged(const AtomicString& newStyleString,
                             AttributeModificationReason);

  void updatePresentationAttributeStyle();

  void inlineStyleChanged();
  void setInlineStyleFromString(const AtomicString&);

  // If the only inherited changes in the parent element are independent,
  // these changes can be directly propagated to this element (the child).
  // If these conditions are met, propagates the changes to the current style
  // and returns the new style. Otherwise, returns null.
  PassRefPtr<ComputedStyle> propagateInheritedProperties(StyleRecalcChange);

  StyleRecalcChange recalcOwnStyle(StyleRecalcChange, Text*);
  inline void checkForEmptyStyleChange();

  void updatePseudoElement(PseudoId, StyleRecalcChange);
  bool updateFirstLetter(Element*);

  inline void createPseudoElementIfNeeded(PseudoId);

  ShadowRoot* shadowRoot() const;

  // FIXME: Everyone should allow author shadows.
  virtual bool areAuthorShadowsAllowed() const { return true; }
  virtual void didAddUserAgentShadowRoot(ShadowRoot&) {}
  virtual bool alwaysCreateUserAgentShadowRoot() const { return false; }

  enum SynchronizationOfLazyAttribute {
    NotInSynchronizationOfLazyAttribute = 0,
    InSynchronizationOfLazyAttribute
  };

  void didAddAttribute(const QualifiedName&, const AtomicString&);
  void willModifyAttribute(const QualifiedName&,
                           const AtomicString& oldValue,
                           const AtomicString& newValue);
  void didModifyAttribute(const QualifiedName&,
                          const AtomicString& oldValue,
                          const AtomicString& newValue);
  void didRemoveAttribute(const QualifiedName&, const AtomicString& oldValue);

  void synchronizeAllAttributes() const;
  void synchronizeAttribute(const QualifiedName&) const;

  void updateId(const AtomicString& oldId, const AtomicString& newId);
  void updateId(TreeScope&,
                const AtomicString& oldId,
                const AtomicString& newId);
  void updateName(const AtomicString& oldName, const AtomicString& newName);

  void clientQuads(Vector<FloatQuad>& quads);

  NodeType getNodeType() const final;
  bool childTypeAllowed(NodeType) const final;

  void setAttributeInternal(size_t index,
                            const QualifiedName&,
                            const AtomicString& value,
                            SynchronizationOfLazyAttribute);
  void appendAttributeInternal(const QualifiedName&,
                               const AtomicString& value,
                               SynchronizationOfLazyAttribute);
  void removeAttributeInternal(size_t index, SynchronizationOfLazyAttribute);
  void attributeChangedFromParserOrByCloning(const QualifiedName&,
                                             const AtomicString&,
                                             AttributeModificationReason);

  bool pseudoStyleCacheIsInvalid(const ComputedStyle* currentStyle,
                                 ComputedStyle* newStyle);

  void cancelFocusAppearanceUpdate();

  const ComputedStyle* virtualEnsureComputedStyle(
      PseudoId pseudoElementSpecifier = PseudoIdNone) override {
    return ensureComputedStyle(pseudoElementSpecifier);
  }

  inline void updateCallbackSelectors(const ComputedStyle* oldStyle,
                                      const ComputedStyle* newStyle);
  inline void removeCallbackSelectors();
  inline void addCallbackSelectors();

  // cloneNode is private so that non-virtual cloneElementWithChildren and
  // cloneElementWithoutChildren are used instead.
  Node* cloneNode(bool deep) override;
  virtual Element* cloneElementWithoutAttributesAndChildren();

  QualifiedName m_tagName;

  void updateNamedItemRegistration(const AtomicString& oldName,
                                   const AtomicString& newName);
  void updateExtraNamedItemRegistration(const AtomicString& oldName,
                                        const AtomicString& newName);

  void createUniqueElementData();

  bool shouldInvalidateDistributionWhenAttributeChanged(ElementShadow*,
                                                        const QualifiedName&,
                                                        const AtomicString&);

  ElementRareData* elementRareData() const;
  ElementRareData& ensureElementRareData();

  void removeAttrNodeList();
  void detachAllAttrNodesFromElement();
  void detachAttrNodeFromElementWithValue(Attr*, const AtomicString& value);
  void detachAttrNodeAtIndex(Attr*, size_t index);

  v8::Local<v8::Object> wrapCustomElement(
      v8::Isolate*,
      v8::Local<v8::Object> creationContext);

  Member<ElementData> m_elementData;
};

DEFINE_NODE_TYPE_CASTS(Element, isElementNode());
template <typename T>
bool isElementOfType(const Node&);
template <>
inline bool isElementOfType<const Element>(const Node& node) {
  return node.isElementNode();
}
template <typename T>
inline bool isElementOfType(const Element& element) {
  return isElementOfType<T>(static_cast<const Node&>(element));
}
template <>
inline bool isElementOfType<const Element>(const Element&) {
  return true;
}

// Type casting.
template <typename T>
inline T& toElement(Node& node) {
  SECURITY_DCHECK(isElementOfType<const T>(node));
  return static_cast<T&>(node);
}
template <typename T>
inline T* toElement(Node* node) {
  SECURITY_DCHECK(!node || isElementOfType<const T>(*node));
  return static_cast<T*>(node);
}
template <typename T>
inline const T& toElement(const Node& node) {
  SECURITY_DCHECK(isElementOfType<const T>(node));
  return static_cast<const T&>(node);
}
template <typename T>
inline const T* toElement(const Node* node) {
  SECURITY_DCHECK(!node || isElementOfType<const T>(*node));
  return static_cast<const T*>(node);
}

template <typename T>
inline T& toElementOrDie(Node& node) {
  CHECK(isElementOfType<const T>(node));
  return static_cast<T&>(node);
}
template <typename T>
inline T* toElementOrDie(Node* node) {
  CHECK(!node || isElementOfType<const T>(*node));
  return static_cast<T*>(node);
}
template <typename T>
inline const T& toElementOrDie(const Node& node) {
  CHECK(isElementOfType<const T>(node));
  return static_cast<const T&>(node);
}
template <typename T>
inline const T* toElementOrDie(const Node* node) {
  CHECK(!node || isElementOfType<const T>(*node));
  return static_cast<const T*>(node);
}

inline bool isDisabledFormControl(const Node* node) {
  return node->isElementNode() && toElement(node)->isDisabledFormControl();
}

inline Element* Node::parentElement() const {
  ContainerNode* parent = parentNode();
  return parent && parent->isElementNode() ? toElement(parent) : nullptr;
}

inline bool Element::fastHasAttribute(const QualifiedName& name) const {
#if DCHECK_IS_ON()
  DCHECK(fastAttributeLookupAllowed(name));
#endif
  return elementData() &&
         elementData()->attributes().findIndex(name) != kNotFound;
}

inline const AtomicString& Element::fastGetAttribute(
    const QualifiedName& name) const {
#if DCHECK_IS_ON()
  DCHECK(fastAttributeLookupAllowed(name));
#endif
  if (elementData()) {
    if (const Attribute* attribute = elementData()->attributes().find(name))
      return attribute->value();
  }
  return nullAtom;
}

inline AttributeCollection Element::attributes() const {
  if (!elementData())
    return AttributeCollection();
  synchronizeAllAttributes();
  return elementData()->attributes();
}

inline AttributeCollection Element::attributesWithoutUpdate() const {
  if (!elementData())
    return AttributeCollection();
  return elementData()->attributes();
}

inline bool Element::hasAttributes() const {
  return !attributes().isEmpty();
}

inline const AtomicString& Element::idForStyleResolution() const {
  DCHECK(hasID());
  return elementData()->idForStyleResolution();
}

inline const AtomicString& Element::getIdAttribute() const {
  return hasID() ? fastGetAttribute(HTMLNames::idAttr) : nullAtom;
}

inline const AtomicString& Element::getNameAttribute() const {
  return hasName() ? fastGetAttribute(HTMLNames::nameAttr) : nullAtom;
}

inline const AtomicString& Element::getClassAttribute() const {
  if (!hasClass())
    return nullAtom;
  if (isSVGElement())
    return getAttribute(HTMLNames::classAttr);
  return fastGetAttribute(HTMLNames::classAttr);
}

inline void Element::setIdAttribute(const AtomicString& value) {
  setAttribute(HTMLNames::idAttr, value);
}

inline const SpaceSplitString& Element::classNames() const {
  DCHECK(hasClass());
  DCHECK(elementData());
  return elementData()->classNames();
}

inline bool Element::hasID() const {
  return elementData() && elementData()->hasID();
}

inline bool Element::hasClass() const {
  return elementData() && elementData()->hasClass();
}

inline UniqueElementData& Element::ensureUniqueElementData() {
  if (!elementData() || !elementData()->isUnique())
    createUniqueElementData();
  return toUniqueElementData(*m_elementData);
}

inline Node::InsertionNotificationRequest Node::insertedInto(
    ContainerNode* insertionPoint) {
  DCHECK(!childNeedsStyleInvalidation());
  DCHECK(!needsStyleInvalidation());
  DCHECK(insertionPoint->isConnected() || insertionPoint->isInShadowTree() ||
         isContainerNode());
  if (insertionPoint->isConnected()) {
    setFlag(IsConnectedFlag);
    insertionPoint->document().incrementNodeCount();
  }
  if (parentOrShadowHostNode()->isInShadowTree())
    setFlag(IsInShadowTreeFlag);
  if (childNeedsDistributionRecalc() &&
      !insertionPoint->childNeedsDistributionRecalc())
    insertionPoint->markAncestorsWithChildNeedsDistributionRecalc();
  return InsertionDone;
}

inline void Node::removedFrom(ContainerNode* insertionPoint) {
  DCHECK(insertionPoint->isConnected() || isContainerNode() ||
         isInShadowTree());
  if (insertionPoint->isConnected()) {
    clearFlag(IsConnectedFlag);
    insertionPoint->document().decrementNodeCount();
  }
  if (isInShadowTree() && !containingTreeScope().rootNode().isShadowRoot())
    clearFlag(IsInShadowTreeFlag);
  if (AXObjectCache* cache = document().existingAXObjectCache())
    cache->remove(this);
}

inline void Element::invalidateStyleAttribute() {
  DCHECK(elementData());
  elementData()->m_styleAttributeIsDirty = true;
}

inline const StylePropertySet* Element::presentationAttributeStyle() {
  if (!elementData())
    return nullptr;
  if (elementData()->m_presentationAttributeStyleIsDirty)
    updatePresentationAttributeStyle();
  // Need to call elementData() again since updatePresentationAttributeStyle()
  // might swap it with a UniqueElementData.
  return elementData()->presentationAttributeStyle();
}

inline void Element::setTagNameForCreateElementNS(
    const QualifiedName& tagName) {
  // We expect this method to be called only to reset the prefix.
  DCHECK_EQ(tagName.localName(), m_tagName.localName());
  DCHECK_EQ(tagName.namespaceURI(), m_tagName.namespaceURI());
  m_tagName = tagName;
}

inline AtomicString Element::localNameForSelectorMatching() const {
  if (isHTMLElement() || !document().isHTMLDocument())
    return localName();
  return localName().lower();
}

inline bool isShadowHost(const Node* node) {
  return node && node->isElementNode() && toElement(node)->shadow();
}

inline bool isShadowHost(const Node& node) {
  return node.isElementNode() && toElement(node).shadow();
}

inline bool isShadowHost(const Element* element) {
  return element && element->shadow();
}

inline bool isShadowHost(const Element& element) {
  return element.shadow();
}

inline bool isAtShadowBoundary(const Element* element) {
  if (!element)
    return false;
  ContainerNode* parentNode = element->parentNode();
  return parentNode && parentNode->isShadowRoot();
}

// These macros do the same as their NODE equivalents but additionally provide a
// template specialization for isElementOfType<>() so that the Traversal<> API
// works for these Element types.
#define DEFINE_ELEMENT_TYPE_CASTS(thisType, predicate)            \
  template <>                                                     \
  inline bool isElementOfType<const thisType>(const Node& node) { \
    return node.predicate;                                        \
  }                                                               \
  DEFINE_NODE_TYPE_CASTS(thisType, predicate)

#define DEFINE_ELEMENT_TYPE_CASTS_WITH_FUNCTION(thisType)         \
  template <>                                                     \
  inline bool isElementOfType<const thisType>(const Node& node) { \
    return is##thisType(node);                                    \
  }                                                               \
  DEFINE_NODE_TYPE_CASTS_WITH_FUNCTION(thisType)

#define DECLARE_ELEMENT_FACTORY_WITH_TAGNAME(T) \
  static T* create(const QualifiedName&, Document&)
#define DEFINE_ELEMENT_FACTORY_WITH_TAGNAME(T)                     \
  T* T::create(const QualifiedName& tagName, Document& document) { \
    return new T(tagName, document);                               \
  }

}  // namespace blink

#endif  // Element_h