/*
 * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
 *           (C) 1999 Antti Koivisto (koivisto@kde.org)
 *           (C) 2001 Dirk Mueller (mueller@kde.org)
 * Copyright (C) 2004-2011, 2014 Apple Inc. All rights reserved.
 * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
 * (http://www.torchmobile.com/)
 *
 * 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 Node_h
#define Node_h

#include "bindings/core/v8/ExceptionState.h"
#include "bindings/core/v8/NodeOrString.h"
#include "bindings/core/v8/TraceWrapperMember.h"
#include "core/CoreExport.h"
#include "core/dom/MutationObserver.h"
#include "core/dom/SimulatedClickOptions.h"
#include "core/dom/TreeScope.h"
#include "core/editing/EditingBoundary.h"
#include "core/events/EventTarget.h"
#include "core/style/ComputedStyleConstants.h"
#include "platform/geometry/LayoutRect.h"
#include "platform/heap/Handle.h"
#include "wtf/Compiler.h"
#include "wtf/Forward.h"

// This needs to be here because Element.cpp also depends on it.
#define DUMP_NODE_STATISTICS 0

namespace blink {

class ContainerNode;
class Document;
class Element;
class ElementShadow;
class Event;
class ExceptionState;
class GetRootNodeOptions;
class HTMLQualifiedName;
class HTMLSlotElement;
class IntRect;
class EventDispatchHandlingState;
class NodeList;
class NodeListsNodeData;
class NodeRareData;
class PlatformMouseEvent;
class QualifiedName;
class RegisteredEventListener;
class LayoutBox;
class LayoutBoxModelObject;
class LayoutObject;
class ComputedStyle;
class SVGQualifiedName;
class ShadowRoot;
template <typename NodeType>
class StaticNodeTypeList;
using StaticNodeList = StaticNodeTypeList<Node>;
class StyleChangeReasonForTracing;
class Text;

const int nodeStyleChangeShift = 18;
const int nodeCustomElementShift = 20;

enum StyleChangeType {
  NoStyleChange = 0,
  LocalStyleChange = 1 << nodeStyleChangeShift,
  SubtreeStyleChange = 2 << nodeStyleChangeShift,
  NeedsReattachStyleChange = 3 << nodeStyleChangeShift,
};

enum class CustomElementState {
  // https://dom.spec.whatwg.org/#concept-element-custom-element-state
  Uncustomized = 0,
  Custom = 1 << nodeCustomElementShift,
  Undefined = 2 << nodeCustomElementShift,
  Failed = 3 << nodeCustomElementShift,

  NotDefinedFlag = 2 << nodeCustomElementShift,
};

enum class SlotChangeType {
  Initial,
  Chained,
};

class NodeRareDataBase {
 public:
  LayoutObject* layoutObject() const { return m_layoutObject; }
  void setLayoutObject(LayoutObject* layoutObject) {
    m_layoutObject = layoutObject;
  }

 protected:
  NodeRareDataBase(LayoutObject* layoutObject) : m_layoutObject(layoutObject) {}

 protected:
  // LayoutObjects are fully owned by their DOM node. See LayoutObject's
  // LIFETIME documentation section.
  LayoutObject* m_layoutObject;
};

class Node;
WILL_NOT_BE_EAGERLY_TRACED_CLASS(Node);

// This class represents a DOM node in the DOM tree.
// https://dom.spec.whatwg.org/#interface-node
class CORE_EXPORT Node : public EventTarget {
  DEFINE_WRAPPERTYPEINFO();
  friend class TreeScope;
  friend class TreeScopeAdopter;

 public:
  enum NodeType {
    kElementNode = 1,
    kAttributeNode = 2,
    kTextNode = 3,
    kCdataSectionNode = 4,
    kProcessingInstructionNode = 7,
    kCommentNode = 8,
    kDocumentNode = 9,
    kDocumentTypeNode = 10,
    kDocumentFragmentNode = 11,
  };

  // Entity, EntityReference, and Notation nodes are impossible to create in
  // Blink.  But for compatibility reasons we want these enum values exist in
  // JS, and this enum makes the bindings generation not complain about
  // kEntityReferenceNode being missing from the implementation while not
  // requiring all switch(NodeType) blocks to include this deprecated constant.
  enum DeprecatedNodeType {
    kEntityReferenceNode = 5,
    kEntityNode = 6,
    kNotationNode = 12,
  };

  enum DocumentPosition {
    kDocumentPositionEquivalent = 0x00,
    kDocumentPositionDisconnected = 0x01,
    kDocumentPositionPreceding = 0x02,
    kDocumentPositionFollowing = 0x04,
    kDocumentPositionContains = 0x08,
    kDocumentPositionContainedBy = 0x10,
    kDocumentPositionImplementationSpecific = 0x20,
  };

  // Override operator new to allocate Node subtype objects onto
  // a dedicated heap.
  GC_PLUGIN_IGNORE("crbug.com/443854")
  void* operator new(size_t size) { return allocateObject(size, false); }
  static void* allocateObject(size_t size, bool isEager) {
    ThreadState* state =
        ThreadStateFor<ThreadingTrait<Node>::Affinity>::state();
    const char typeName[] = "blink::Node";
    return ThreadHeap::allocateOnArenaIndex(
        state, size,
        isEager ? BlinkGC::EagerSweepArenaIndex : BlinkGC::NodeArenaIndex,
        GCInfoTrait<EventTarget>::index(), typeName);
  }

  static void dumpStatistics();

  ~Node() override;

  // DOM methods & attributes for Node

  bool hasTagName(const HTMLQualifiedName&) const;
  bool hasTagName(const SVGQualifiedName&) const;
  virtual String nodeName() const = 0;
  virtual String nodeValue() const;
  virtual void setNodeValue(const String&);
  virtual NodeType getNodeType() const = 0;
  ContainerNode* parentNode() const;
  Element* parentElement() const;
  ContainerNode* parentElementOrShadowRoot() const;
  ContainerNode* parentElementOrDocumentFragment() const;
  Node* previousSibling() const { return m_previous; }
  Node* nextSibling() const { return m_next; }
  NodeList* childNodes();
  Node* firstChild() const;
  Node* lastChild() const;
  Node* getRootNode(const GetRootNodeOptions&) const;
  Node& treeRoot() const;
  Node& shadowIncludingRoot() const;
  // closed-shadow-hidden is defined at
  // https://dom.spec.whatwg.org/#concept-closed-shadow-hidden
  bool isClosedShadowHiddenFrom(const Node&) const;

  void prepend(const HeapVector<NodeOrString>&, ExceptionState&);
  void append(const HeapVector<NodeOrString>&, ExceptionState&);
  void before(const HeapVector<NodeOrString>&, ExceptionState&);
  void after(const HeapVector<NodeOrString>&, ExceptionState&);
  void replaceWith(const HeapVector<NodeOrString>&, ExceptionState&);
  void remove(ExceptionState& = ASSERT_NO_EXCEPTION);

  Node* pseudoAwareNextSibling() const;
  Node* pseudoAwarePreviousSibling() const;
  Node* pseudoAwareFirstChild() const;
  Node* pseudoAwareLastChild() const;

  const KURL& baseURI() const;

  Node* insertBefore(Node* newChild,
                     Node* refChild,
                     ExceptionState& = ASSERT_NO_EXCEPTION);
  Node* replaceChild(Node* newChild,
                     Node* oldChild,
                     ExceptionState& = ASSERT_NO_EXCEPTION);
  Node* removeChild(Node* child, ExceptionState& = ASSERT_NO_EXCEPTION);
  Node* appendChild(Node* newChild, ExceptionState& = ASSERT_NO_EXCEPTION);

  bool hasChildren() const { return firstChild(); }
  virtual Node* cloneNode(bool deep) = 0;
  void normalize();

  bool isEqualNode(Node*) const;
  bool isSameNode(const Node* other) const { return this == other; }
  bool isDefaultNamespace(const AtomicString& namespaceURI) const;
  const AtomicString& lookupPrefix(const AtomicString& namespaceURI) const;
  const AtomicString& lookupNamespaceURI(const String& prefix) const;

  String textContent(bool convertBRsToNewlines = false) const;
  void setTextContent(const String&);

  bool supportsAltText();

  // Other methods (not part of DOM)

  bool isElementNode() const { return getFlag(IsElementFlag); }
  bool isContainerNode() const { return getFlag(IsContainerFlag); }
  bool isTextNode() const { return getFlag(IsTextFlag); }
  bool isHTMLElement() const { return getFlag(IsHTMLFlag); }
  bool isSVGElement() const { return getFlag(IsSVGFlag); }

  DISABLE_CFI_PERF bool isPseudoElement() const {
    return getPseudoId() != PseudoIdNone;
  }
  DISABLE_CFI_PERF bool isBeforePseudoElement() const {
    return getPseudoId() == PseudoIdBefore;
  }
  DISABLE_CFI_PERF bool isAfterPseudoElement() const {
    return getPseudoId() == PseudoIdAfter;
  }
  DISABLE_CFI_PERF bool isFirstLetterPseudoElement() const {
    return getPseudoId() == PseudoIdFirstLetter;
  }
  virtual PseudoId getPseudoId() const { return PseudoIdNone; }

  CustomElementState getCustomElementState() const {
    return static_cast<CustomElementState>(m_nodeFlags &
                                           CustomElementStateMask);
  }
  void setCustomElementState(CustomElementState);
  bool isV0CustomElement() const { return getFlag(V0CustomElementFlag); }
  enum V0CustomElementState {
    V0NotCustomElement = 0,
    V0WaitingForUpgrade = 1 << 0,
    V0Upgraded = 1 << 1
  };
  V0CustomElementState getV0CustomElementState() const {
    return isV0CustomElement()
               ? (getFlag(V0CustomElementUpgradedFlag) ? V0Upgraded
                                                       : V0WaitingForUpgrade)
               : V0NotCustomElement;
  }
  void setV0CustomElementState(V0CustomElementState newState);

  virtual bool isMediaControlElement() const { return false; }
  virtual bool isMediaControls() const { return false; }
  virtual bool isTextTrackContainer() const { return false; }
  virtual bool isVTTElement() const { return false; }
  virtual bool isAttributeNode() const { return false; }
  virtual bool isCharacterDataNode() const { return false; }
  virtual bool isFrameOwnerElement() const { return false; }

  bool isStyledElement() const;

  bool isDocumentNode() const;
  bool isTreeScope() const;
  bool isDocumentFragment() const { return getFlag(IsDocumentFragmentFlag); }
  bool isShadowRoot() const { return isDocumentFragment() && isTreeScope(); }
  bool isInsertionPoint() const { return getFlag(IsInsertionPointFlag); }

  bool canParticipateInFlatTree() const;
  bool isActiveSlotOrActiveInsertionPoint() const;
  // A re-distribution across v0 and v1 shadow trees is not supported.
  bool isSlotable() const {
    return isTextNode() || (isElementNode() && !isInsertionPoint());
  }
  AtomicString slotName() const;

  bool hasCustomStyleCallbacks() const {
    return getFlag(HasCustomStyleCallbacksFlag);
  }

  // If this node is in a shadow tree, returns its shadow host. Otherwise,
  // returns nullptr.
  // TODO(kochi): crbug.com/507413 ownerShadowHost() can return nullptr even
  // when it is in a shadow tree but its root is detached from its host. This
  // can happen when handling queued events (e.g. during execCommand()).
  Element* ownerShadowHost() const;
  // crbug.com/569532: containingShadowRoot() can return nullptr even if
  // isInShadowTree() returns true.
  // This can happen when handling queued events (e.g. during execCommand())
  ShadowRoot* containingShadowRoot() const;
  ShadowRoot* youngestShadowRoot() const;

  // Returns nullptr, a child of ShadowRoot, or a legacy shadow root.
  Node* nonBoundaryShadowTreeRootNode();

  // Node's parent, shadow tree host.
  ContainerNode* parentOrShadowHostNode() const;
  Element* parentOrShadowHostElement() const;
  void setParentOrShadowHostNode(ContainerNode*);

  // Knows about all kinds of hosts.
  ContainerNode* parentOrShadowHostOrTemplateHostNode() const;

  // Returns the parent node, but nullptr if the parent node is a ShadowRoot.
  ContainerNode* nonShadowBoundaryParentNode() const;

  // Returns the enclosing event parent Element (or self) that, when clicked,
  // would trigger a navigation.
  Element* enclosingLinkEventParentOrSelf() const;

  // These low-level calls give the caller responsibility for maintaining the
  // integrity of the tree.
  void setPreviousSibling(Node* previous) {
    m_previous = previous;
    ScriptWrappableVisitor::writeBarrier(this, m_previous);
  }
  void setNextSibling(Node* next) {
    m_next = next;
    ScriptWrappableVisitor::writeBarrier(this, m_next);
  }

  virtual bool canContainRangeEndPoint() const { return false; }

  // For <link> and <style> elements.
  virtual bool sheetLoaded() { return true; }
  enum LoadedSheetErrorStatus {
    NoErrorLoadingSubresource,
    ErrorOccurredLoadingSubresource
  };
  virtual void notifyLoadedSheetAndAllCriticalSubresources(
      LoadedSheetErrorStatus) {}
  virtual void startLoadingDynamicSheet() { NOTREACHED(); }

  bool hasName() const {
    DCHECK(!isTextNode());
    return getFlag(HasNameOrIsEditingTextFlag);
  }

  bool isUserActionElement() const { return getFlag(IsUserActionElementFlag); }
  void setUserActionElement(bool flag) {
    setFlag(flag, IsUserActionElementFlag);
  }

  bool isActive() const {
    return isUserActionElement() && isUserActionElementActive();
  }
  bool inActiveChain() const {
    return isUserActionElement() && isUserActionElementInActiveChain();
  }
  bool isDragged() const {
    return isUserActionElement() && isUserActionElementDragged();
  }
  bool isHovered() const {
    return isUserActionElement() && isUserActionElementHovered();
  }
  // Note: As a shadow host whose root with delegatesFocus=false may become
  // focused state when an inner element gets focused, in that case more than
  // one elements in a document can return true for |isFocused()|.  Use
  // Element::isFocusedElementInDocument() or Document::focusedElement() to
  // check which element is exactly focused.
  bool isFocused() const {
    return isUserActionElement() && isUserActionElementFocused();
  }

  bool needsAttach() const {
    return getStyleChangeType() == NeedsReattachStyleChange;
  }
  bool needsStyleRecalc() const {
    return getStyleChangeType() != NoStyleChange;
  }
  StyleChangeType getStyleChangeType() const {
    return static_cast<StyleChangeType>(m_nodeFlags & StyleChangeMask);
  }
  bool childNeedsStyleRecalc() const {
    return getFlag(ChildNeedsStyleRecalcFlag);
  }
  bool isLink() const { return getFlag(IsLinkFlag); }
  bool isEditingText() const {
    DCHECK(isTextNode());
    return getFlag(HasNameOrIsEditingTextFlag);
  }

  void setHasName(bool f) {
    DCHECK(!isTextNode());
    setFlag(f, HasNameOrIsEditingTextFlag);
  }
  void setChildNeedsStyleRecalc() { setFlag(ChildNeedsStyleRecalcFlag); }
  void clearChildNeedsStyleRecalc() { clearFlag(ChildNeedsStyleRecalcFlag); }

  void setNeedsStyleRecalc(StyleChangeType, const StyleChangeReasonForTracing&);
  void clearNeedsStyleRecalc();

  bool needsReattachLayoutTree() { return getFlag(NeedsReattachLayoutTree); }
  bool childNeedsReattachLayoutTree() {
    return getFlag(ChildNeedsReattachLayoutTree);
  }

  void setNeedsReattachLayoutTree();
  void setChildNeedsReattachLayoutTree() {
    setFlag(ChildNeedsReattachLayoutTree);
  }

  void clearNeedsReattachLayoutTree() { clearFlag(NeedsReattachLayoutTree); }
  void clearChildNeedsReattachLayoutTree() {
    clearFlag(ChildNeedsReattachLayoutTree);
  }

  void markAncestorsWithChildNeedsReattachLayoutTree();

  bool needsDistributionRecalc() const;

  bool childNeedsDistributionRecalc() const {
    return getFlag(ChildNeedsDistributionRecalcFlag);
  }
  void setChildNeedsDistributionRecalc() {
    setFlag(ChildNeedsDistributionRecalcFlag);
  }
  void clearChildNeedsDistributionRecalc() {
    clearFlag(ChildNeedsDistributionRecalcFlag);
  }
  void markAncestorsWithChildNeedsDistributionRecalc();

  bool childNeedsStyleInvalidation() const {
    return getFlag(ChildNeedsStyleInvalidationFlag);
  }
  void setChildNeedsStyleInvalidation() {
    setFlag(ChildNeedsStyleInvalidationFlag);
  }
  void clearChildNeedsStyleInvalidation() {
    clearFlag(ChildNeedsStyleInvalidationFlag);
  }
  void markAncestorsWithChildNeedsStyleInvalidation();
  bool needsStyleInvalidation() const {
    return getFlag(NeedsStyleInvalidationFlag);
  }
  void clearNeedsStyleInvalidation() { clearFlag(NeedsStyleInvalidationFlag); }
  void setNeedsStyleInvalidation();

  void updateDistribution();

  void setIsLink(bool f);

  bool hasEventTargetData() const { return getFlag(HasEventTargetDataFlag); }
  void setHasEventTargetData(bool flag) {
    setFlag(flag, HasEventTargetDataFlag);
  }

  virtual void setFocused(bool flag);
  virtual void setActive(bool flag = true);
  virtual void setDragged(bool flag);
  virtual void setHovered(bool flag = true);

  virtual int tabIndex() const;

  virtual Node* focusDelegate();
  // This is called only when the node is focused.
  virtual bool shouldHaveFocusAppearance() const;

  // Whether the node is inert. This can't be in Element because text nodes
  // must be recognized as inert to prevent text selection.
  bool isInert() const;

  virtual LayoutRect boundingBox() const;
  IntRect pixelSnappedBoundingBox() const {
    return pixelSnappedIntRect(boundingBox());
  }

  unsigned nodeIndex() const;

  // Returns the DOM ownerDocument attribute. This method never returns null,
  // except in the case of a Document node.
  Document* ownerDocument() const;

  // Returns the document associated with this node. A Document node returns
  // itself.
  Document& document() const { return treeScope().document(); }

  TreeScope& treeScope() const {
    DCHECK(m_treeScope);
    return *m_treeScope;
  }

  TreeScope& containingTreeScope() const {
    DCHECK(isInTreeScope());
    return *m_treeScope;
  }

  bool inActiveDocument() const;

  // Returns true if this node is connected to a document, false otherwise.
  // See https://dom.spec.whatwg.org/#connected for the definition.
  bool isConnected() const { return getFlag(IsConnectedFlag); }

  bool isInDocumentTree() const { return isConnected() && !isInShadowTree(); }
  bool isInShadowTree() const { return getFlag(IsInShadowTreeFlag); }
  bool isInTreeScope() const {
    return getFlag(
        static_cast<NodeFlags>(IsConnectedFlag | IsInShadowTreeFlag));
  }

  ElementShadow* parentElementShadow() const;
  bool isInV1ShadowTree() const;
  bool isInV0ShadowTree() const;
  bool isChildOfV1ShadowHost() const;
  bool isChildOfV0ShadowHost() const;
  ShadowRoot* v1ShadowRootOfParent() const;

  bool isDocumentTypeNode() const { return getNodeType() == kDocumentTypeNode; }
  virtual bool childTypeAllowed(NodeType) const { return false; }
  unsigned countChildren() const;

  bool isDescendantOf(const Node*) const;
  bool contains(const Node*) const;
  bool isShadowIncludingInclusiveAncestorOf(const Node*) const;
  bool containsIncludingHostElements(const Node&) const;
  Node* commonAncestor(const Node&,
                       ContainerNode* (*parent)(const Node&)) const;

  // Number of DOM 16-bit units contained in node. Note that laid out text
  // length can be different - e.g. because of css-transform:capitalize breaking
  // up precomposed characters and ligatures.
  virtual int maxCharacterOffset() const;

  // Whether or not a selection can be started in this object
  virtual bool canStartSelection() const;

  // -----------------------------------------------------------------------------
  // Integration with layout tree

  // As layoutObject() includes a branch you should avoid calling it repeatedly
  // in hot code paths.
  // Note that if a Node has a layoutObject, it's parentNode is guaranteed to
  // have one as well.
  LayoutObject* layoutObject() const {
    return hasRareData() ? m_data.m_rareData->layoutObject()
                         : m_data.m_layoutObject;
  }
  void setLayoutObject(LayoutObject* layoutObject) {
    if (hasRareData())
      m_data.m_rareData->setLayoutObject(layoutObject);
    else
      m_data.m_layoutObject = layoutObject;
  }

  // Use these two methods with caution.
  LayoutBox* layoutBox() const;
  LayoutBoxModelObject* layoutBoxModelObject() const;

  struct AttachContext {
    STACK_ALLOCATED();
    ComputedStyle* resolvedStyle = nullptr;
    bool performingReattach = false;
    bool clearInvalidation = false;

    AttachContext() {}
  };

  // Attaches this node to the layout tree. This calculates the style to be
  // applied to the node and creates an appropriate LayoutObject which will be
  // inserted into the tree (except when the style has display: none). This
  // makes the node visible in the FrameView.
  virtual void attachLayoutTree(const AttachContext& = AttachContext());

  // Detaches the node from the layout tree, making it invisible in the rendered
  // view. This method will remove the node's layout object from the layout tree
  // and delete it.
  virtual void detachLayoutTree(const AttachContext& = AttachContext());

  void reattachLayoutTree(const AttachContext& = AttachContext());
  void lazyReattachIfAttached();

  // Returns true if recalcStyle should be called on the object, if there is
  // such a method (on Document and Element).
  bool shouldCallRecalcStyle(StyleRecalcChange);

  // Wrapper for nodes that don't have a layoutObject, but still cache the style
  // (like HTMLOptionElement).
  ComputedStyle* mutableComputedStyle() const;
  const ComputedStyle* computedStyle() const;
  const ComputedStyle* parentComputedStyle() const;

  const ComputedStyle& computedStyleRef() const;

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

  // -----------------------------------------------------------------------------
  // Notification of document structure changes (see ContainerNode.h for more
  // notification methods)
  //
  // At first, Blinkt notifies the node that it has been inserted into the
  // document. This is called during document parsing, and also when a node is
  // added through the DOM methods insertBefore(), appendChild() or
  // replaceChild(). The call happens _after_ the node has been added to the
  // tree.  This is similar to the DOMNodeInsertedIntoDocument DOM event, but
  // does not require the overhead of event dispatching.
  //
  // Blink notifies this callback regardless if the subtree of the node is a
  // document tree or a floating subtree.  Implementation can determine the type
  // of subtree by seeing insertionPoint->isConnected().  For a performance
  // reason, notifications are delivered only to ContainerNode subclasses if the
  // insertionPoint is out of document.
  //
  // There are another callback named didNotifySubtreeInsertionsToDocument(),
  // which is called after all the descendant is notified, if this node was
  // inserted into the document tree. Only a few subclasses actually need
  // this. To utilize this, the node should return
  // InsertionShouldCallDidNotifySubtreeInsertions from insertedInto().
  //
  enum InsertionNotificationRequest {
    InsertionDone,
    InsertionShouldCallDidNotifySubtreeInsertions
  };

  virtual InsertionNotificationRequest insertedInto(
      ContainerNode* insertionPoint);
  virtual void didNotifySubtreeInsertionsToDocument() {}

  // Notifies the node that it is no longer part of the tree.
  //
  // This is a dual of insertedInto(), and is similar to the
  // DOMNodeRemovedFromDocument DOM event, but does not require the overhead of
  // event dispatching, and is called _after_ the node is removed from the tree.
  //
  virtual void removedFrom(ContainerNode* insertionPoint);

  // FIXME(dominicc): This method is not debug-only--it is used by
  // Tracing--rename it to something indicative.
  String debugName() const;

#ifndef NDEBUG
  String toString() const;
  String toTreeStringForThis() const;
  String toFlatTreeStringForThis() const;
  void printNodePathTo(std::ostream&) const;
  String toMarkedTreeString(const Node* markedNode1,
                            const char* markedLabel1,
                            const Node* markedNode2 = nullptr,
                            const char* markedLabel2 = nullptr) const;
  String toMarkedFlatTreeString(const Node* markedNode1,
                                const char* markedLabel1,
                                const Node* markedNode2 = nullptr,
                                const char* markedLabel2 = nullptr) const;
  void showTreeForThisAcrossFrame() const;
#endif

  NodeListsNodeData* nodeLists();
  void clearNodeLists();

  virtual bool willRespondToMouseMoveEvents();
  virtual bool willRespondToMouseClickEvents();
  virtual bool willRespondToTouchEvents();

  enum ShadowTreesTreatment {
    TreatShadowTreesAsDisconnected,
    TreatShadowTreesAsComposed
  };

  unsigned short compareDocumentPosition(
      const Node*,
      ShadowTreesTreatment = TreatShadowTreesAsDisconnected) const;

  Node* toNode() final;

  const AtomicString& interfaceName() const override;
  ExecutionContext* getExecutionContext() const final;

  void removeAllEventListeners() override;
  void removeAllEventListenersRecursively();

  // Handlers to do/undo actions on the target node before an event is
  // dispatched to it and after the event has been dispatched.  The data pointer
  // is handed back by the preDispatch and passed to postDispatch.
  virtual EventDispatchHandlingState* preDispatchEventHandler(Event*) {
    return nullptr;
  }
  virtual void postDispatchEventHandler(Event*, EventDispatchHandlingState*) {}

  void dispatchScopedEvent(Event*);

  virtual void handleLocalEvents(Event&);

  void dispatchSubtreeModifiedEvent();
  DispatchEventResult dispatchDOMActivateEvent(int detail,
                                               Event& underlyingEvent);

  void dispatchMouseEvent(const PlatformMouseEvent&,
                          const AtomicString& eventType,
                          int clickCount = 0,
                          Node* relatedTarget = nullptr);

  void dispatchSimulatedClick(
      Event* underlyingEvent,
      SimulatedClickMouseEventOptions = SendNoEvents,
      SimulatedClickCreationScope = SimulatedClickCreationScope::FromUserAgent);

  void dispatchInputEvent();

  // Perform the default action for an event.
  virtual void defaultEventHandler(Event*);
  virtual void willCallDefaultEventHandler(const Event&);

  EventTargetData* eventTargetData() override;
  EventTargetData& ensureEventTargetData() override;

  void getRegisteredMutationObserversOfType(
      HeapHashMap<Member<MutationObserver>, MutationRecordDeliveryOptions>&,
      MutationObserver::MutationType,
      const QualifiedName* attributeName);
  void registerMutationObserver(MutationObserver&,
                                MutationObserverOptions,
                                const HashSet<AtomicString>& attributeFilter);
  void unregisterMutationObserver(MutationObserverRegistration*);
  void registerTransientMutationObserver(MutationObserverRegistration*);
  void unregisterTransientMutationObserver(MutationObserverRegistration*);
  void notifyMutationObserversNodeWillDetach();

  unsigned connectedSubframeCount() const;
  void incrementConnectedSubframeCount();
  void decrementConnectedSubframeCount();

  StaticNodeList* getDestinationInsertionPoints();
  HTMLSlotElement* assignedSlot() const;
  HTMLSlotElement* assignedSlotForBinding();

  bool isFinishedParsingChildren() const {
    return getFlag(IsFinishedParsingChildrenFlag);
  }

  void checkSlotChange(SlotChangeType);
  void checkSlotChangeAfterInserted() {
    checkSlotChange(SlotChangeType::Initial);
  }
  void checkSlotChangeBeforeRemoved() {
    checkSlotChange(SlotChangeType::Initial);
  }

  DECLARE_VIRTUAL_TRACE();

  DECLARE_VIRTUAL_TRACE_WRAPPERS();

  unsigned lengthOfContents() const;

  v8::Local<v8::Object> wrap(v8::Isolate*,
                             v8::Local<v8::Object> creationContext) override;
  WARN_UNUSED_RESULT v8::Local<v8::Object> associateWithWrapper(
      v8::Isolate*,
      const WrapperTypeInfo*,
      v8::Local<v8::Object> wrapper) override;

 private:
  enum NodeFlags {
    HasRareDataFlag = 1,

    // Node type flags. These never change once created.
    IsTextFlag = 1 << 1,
    IsContainerFlag = 1 << 2,
    IsElementFlag = 1 << 3,
    IsHTMLFlag = 1 << 4,
    IsSVGFlag = 1 << 5,
    IsDocumentFragmentFlag = 1 << 6,
    IsInsertionPointFlag = 1 << 7,

    // Changes based on if the element should be treated like a link,
    // ex. When setting the href attribute on an <a>.
    IsLinkFlag = 1 << 8,

    // Changes based on :hover, :active and :focus state.
    IsUserActionElementFlag = 1 << 9,

    // Tree state flags. These change when the element is added/removed
    // from a DOM tree.
    IsConnectedFlag = 1 << 10,
    IsInShadowTreeFlag = 1 << 11,

    // Set by the parser when the children are done parsing.
    IsFinishedParsingChildrenFlag = 1 << 12,

    // Flags related to recalcStyle.
    HasCustomStyleCallbacksFlag = 1 << 13,
    ChildNeedsStyleInvalidationFlag = 1 << 14,
    NeedsStyleInvalidationFlag = 1 << 15,
    ChildNeedsDistributionRecalcFlag = 1 << 16,
    ChildNeedsStyleRecalcFlag = 1 << 17,
    StyleChangeMask =
        1 << nodeStyleChangeShift | 1 << (nodeStyleChangeShift + 1),

    CustomElementStateMask = 0x3 << nodeCustomElementShift,

    HasNameOrIsEditingTextFlag = 1 << 22,
    HasEventTargetDataFlag = 1 << 23,

    V0CustomElementFlag = 1 << 24,
    V0CustomElementUpgradedFlag = 1 << 25,

    NeedsReattachLayoutTree = 1 << 26,
    ChildNeedsReattachLayoutTree = 1 << 27,

    DefaultNodeFlags = IsFinishedParsingChildrenFlag | NeedsReattachStyleChange
  };

  // 4 bits remaining.

  bool getFlag(NodeFlags mask) const { return m_nodeFlags & mask; }
  void setFlag(bool f, NodeFlags mask) {
    m_nodeFlags = (m_nodeFlags & ~mask) | (-(int32_t)f & mask);
  }
  void setFlag(NodeFlags mask) { m_nodeFlags |= mask; }
  void clearFlag(NodeFlags mask) { m_nodeFlags &= ~mask; }

  // TODO(mustaq): This is a hack to fix sites with flash objects. We should
  // instead route all PlatformMouseEvents through EventHandler. See
  // crbug.com/665924.
  void createAndDispatchPointerEvent(const AtomicString& mouseEventName,
                                     const PlatformMouseEvent&,
                                     LocalDOMWindow* view);

 protected:
  enum ConstructionType {
    CreateOther = DefaultNodeFlags,
    CreateText = DefaultNodeFlags | IsTextFlag,
    CreateContainer =
        DefaultNodeFlags | ChildNeedsStyleRecalcFlag | IsContainerFlag,
    CreateElement = CreateContainer | IsElementFlag,
    CreateShadowRoot =
        CreateContainer | IsDocumentFragmentFlag | IsInShadowTreeFlag,
    CreateDocumentFragment = CreateContainer | IsDocumentFragmentFlag,
    CreateHTMLElement = CreateElement | IsHTMLFlag,
    CreateSVGElement = CreateElement | IsSVGFlag,
    CreateDocument = CreateContainer | IsConnectedFlag,
    CreateInsertionPoint = CreateHTMLElement | IsInsertionPointFlag,
    CreateEditingText = CreateText | HasNameOrIsEditingTextFlag,
  };

  Node(TreeScope*, ConstructionType);

  virtual void willMoveToNewDocument(Document& oldDocument,
                                     Document& newDocument);
  virtual void didMoveToNewDocument(Document& oldDocument);

  void addedEventListener(const AtomicString& eventType,
                          RegisteredEventListener&) override;
  void removedEventListener(const AtomicString& eventType,
                            const RegisteredEventListener&) override;
  DispatchEventResult dispatchEventInternal(Event*) override;

  static void reattachWhitespaceSiblingsIfNeeded(Text* start);

  bool hasRareData() const { return getFlag(HasRareDataFlag); }

  NodeRareData* rareData() const;
  NodeRareData& ensureRareData();

  void setHasCustomStyleCallbacks() {
    setFlag(true, HasCustomStyleCallbacksFlag);
  }

  void setTreeScope(TreeScope* scope) { m_treeScope = scope; }

  // isTreeScopeInitialized() can be false
  // - in the destruction of Document or ShadowRoot where m_treeScope is set to
  //   null or
  // - in the Node constructor called by these two classes where m_treeScope is
  //   set by TreeScope ctor.
  bool isTreeScopeInitialized() const { return m_treeScope; }

  void markAncestorsWithChildNeedsStyleRecalc();

  void setIsFinishedParsingChildren(bool value) {
    setFlag(value, IsFinishedParsingChildrenFlag);
  }

 private:
  // Gets nodeName without caching AtomicStrings. Used by
  // debugName. Compositor may call debugName from the "impl" thread
  // during "commit". The main thread is stopped at that time, but
  // it is not safe to cache AtomicStrings because those are
  // per-thread.
  virtual String debugNodeName() const;

  bool isUserActionElementActive() const;
  bool isUserActionElementInActiveChain() const;
  bool isUserActionElementDragged() const;
  bool isUserActionElementHovered() const;
  bool isUserActionElementFocused() const;

  void recalcDistribution();

  void setStyleChange(StyleChangeType);

  virtual ComputedStyle* nonLayoutObjectComputedStyle() const {
    return nullptr;
  }

  virtual const ComputedStyle* virtualEnsureComputedStyle(
      PseudoId = PseudoIdNone);

  void trackForDebugging();

  const HeapVector<TraceWrapperMember<MutationObserverRegistration>>*
  mutationObserverRegistry();
  const HeapHashSet<TraceWrapperMember<MutationObserverRegistration>>*
  transientMutationObserverRegistry();

  uint32_t m_nodeFlags;
  Member<ContainerNode> m_parentOrShadowHostNode;
  Member<TreeScope> m_treeScope;
  Member<Node> m_previous;
  Member<Node> m_next;
  // When a node has rare data we move the layoutObject into the rare data.
  union DataUnion {
    DataUnion() : m_layoutObject(nullptr) {}
    // LayoutObjects are fully owned by their DOM node. See LayoutObject's
    // LIFETIME documentation section.
    LayoutObject* m_layoutObject;
    NodeRareDataBase* m_rareData;
  } m_data;
};

inline void Node::setParentOrShadowHostNode(ContainerNode* parent) {
  DCHECK(isMainThread());
  m_parentOrShadowHostNode = parent;
  ScriptWrappableVisitor::writeBarrier(
      this, reinterpret_cast<Node*>(m_parentOrShadowHostNode.get()));
}

inline ContainerNode* Node::parentOrShadowHostNode() const {
  DCHECK(isMainThread());
  return m_parentOrShadowHostNode;
}

inline ContainerNode* Node::parentNode() const {
  return isShadowRoot() ? nullptr : parentOrShadowHostNode();
}

inline void Node::lazyReattachIfAttached() {
  if (needsAttach())
    return;
  if (!inActiveDocument())
    return;

  AttachContext context;
  context.performingReattach = true;

  detachLayoutTree(context);
  markAncestorsWithChildNeedsStyleRecalc();
}

inline bool Node::shouldCallRecalcStyle(StyleRecalcChange change) {
  return change >= IndependentInherit || needsStyleRecalc() ||
         childNeedsStyleRecalc();
}

inline bool isTreeScopeRoot(const Node* node) {
  return !node || node->isDocumentNode() || node->isShadowRoot();
}

inline bool isTreeScopeRoot(const Node& node) {
  return node.isDocumentNode() || node.isShadowRoot();
}

// See the comment at the declaration of ScriptWrappable::fromNode in
// bindings/core/v8/ScriptWrappable.h about why this method is defined here.
inline ScriptWrappable* ScriptWrappable::fromNode(Node* node) {
  return node;
}

// Allow equality comparisons of Nodes by reference or pointer, interchangeably.
DEFINE_COMPARISON_OPERATORS_WITH_REFERENCES(Node)

#define DEFINE_NODE_TYPE_CASTS(thisType, predicate) \
  DEFINE_TYPE_CASTS(thisType, Node, node, node->predicate, node.predicate)

// This requires isClassName(const Node&).
#define DEFINE_NODE_TYPE_CASTS_WITH_FUNCTION(thisType)         \
  DEFINE_TYPE_CASTS(thisType, Node, node, is##thisType(*node), \
                    is##thisType(node))

#define DECLARE_NODE_FACTORY(T) static T* create(Document&)
#define DEFINE_NODE_FACTORY(T) \
  T* T::create(Document& document) { return new T(document); }

CORE_EXPORT std::ostream& operator<<(std::ostream&, const Node&);
CORE_EXPORT std::ostream& operator<<(std::ostream&, const Node*);

}  // namespace blink

#ifndef NDEBUG
// Outside the WebCore namespace for ease of invocation from gdb.
void showNode(const blink::Node*);
void showTree(const blink::Node*);
void showNodePath(const blink::Node*);
#endif

#endif  // Node_h