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Implementation

Mercurial (c2593a3058af)

VCS Links

AutoFrameConstructionItem

AutoFrameConstructionItemList

ContainingBlockType

FrameConstructionData

FrameConstructionDataByDisplay

FrameConstructionDataByInt

FrameConstructionDataByTag

FrameConstructionItem

FrameConstructionItemList

FreeFCItemLink

Func

InsertionKind

InsertionPoint

Iterator

Operation

ParentType

PseudoParentData

RemoveFlags

RubyWhitespaceType

SiblingDirection

UndisplayedItem

XBLBindingLoadInfo

nsCSSFrameConstructor

Macros

Line Code
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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/*
 * construction of a frame tree that is nearly isomorphic to the content
 * tree and updating of that tree in response to dynamic changes
 */

#ifndef nsCSSFrameConstructor_h___
#define nsCSSFrameConstructor_h___

#include "mozilla/ArenaAllocator.h"
#include "mozilla/Attributes.h"
#include "mozilla/LinkedList.h"
#include "mozilla/Maybe.h"
#include "mozilla/RestyleManager.h"
#include "mozilla/ScrollStyles.h"

#include "nsCOMPtr.h"
#include "nsILayoutHistoryState.h"
#include "nsQuoteList.h"
#include "nsCounterManager.h"
#include "nsIAnonymousContentCreator.h"
#include "nsFrameManager.h"

struct nsFrameItems;
struct nsStyleDisplay;
struct nsGenConInitializer;

class nsContainerFrame;
class nsFirstLineFrame;
class nsFirstLetterFrame;
class nsCSSAnonBoxPseudoStaticAtom;
class nsIDocument;
class nsPageContentFrame;
struct PendingBinding;

class nsFrameConstructorState;

namespace mozilla {

class ComputedStyle;

namespace dom {

class CharacterData;
class Text;
class FlattenedChildIterator;

} // namespace dom
} // namespace mozilla

class nsCSSFrameConstructor final : public nsFrameManager
{
public:
  typedef mozilla::ComputedStyle ComputedStyle;
  typedef mozilla::CSSPseudoElementType CSSPseudoElementType;
  typedef mozilla::dom::Element Element;
  typedef mozilla::dom::Text Text;

  // FIXME(emilio): Is this really needed?
  friend class mozilla::RestyleManager;

  nsCSSFrameConstructor(nsIDocument* aDocument, nsIPresShell* aPresShell);
  ~nsCSSFrameConstructor() {
    MOZ_ASSERT(mFCItemsInUse == 0);
  }

  // get the alternate text for a content node
  static void GetAlternateTextFor(Element* aContent,
                                  nsAtom* aTag,  // content object's tag
                                  nsAString& aAltText);

private:
  nsCSSFrameConstructor(const nsCSSFrameConstructor& aCopy) = delete;
  nsCSSFrameConstructor& operator=(const nsCSSFrameConstructor& aCopy) = delete;

public:
  /**
   * Whether insertion should be done synchronously or asynchronously.
   *
   * Generally, insertion is synchronous if we're entering frame construction
   * from restyle processing, and async if we're removing stuff, or need to
   * reconstruct some ancestor.
   *
   * Note that constructing async from frame construction will post a restyle
   * event, but won't need another whole refresh driver tick to go in. Instead
   * change hint processing will keep going as long as there are changes in the
   * queue.
   */
  enum class InsertionKind
  {
    Sync,
    Async,
  };

  mozilla::RestyleManager* RestyleManager() const
    { return mPresShell->GetPresContext()->RestyleManager(); }

  nsIFrame* ConstructRootFrame();

  void ReconstructDocElementHierarchy(InsertionKind);


private:


  enum Operation {
    CONTENTAPPEND,
    CONTENTINSERT
  };

  // aChild is the child being inserted for inserts, and the first
  // child being appended for appends.
  bool MaybeConstructLazily(Operation aOperation, nsIContent* aChild);

#ifdef DEBUG
  void CheckBitsForLazyFrameConstruction(nsIContent* aParent);
#else
  void CheckBitsForLazyFrameConstruction(nsIContent*) {}
#endif

  // Issues a single ContentInserted for each child in the range
  // [aStartChild, aEndChild).
  void IssueSingleInsertNofications(nsIContent* aStartChild,
                                    nsIContent* aEndChild,
                                    InsertionKind);

  /**
   * Data that represents an insertion point for some child content.
   */
  struct InsertionPoint
  {
    InsertionPoint()
      : mParentFrame(nullptr)
      , mContainer(nullptr)
    {}

    InsertionPoint(nsContainerFrame* aParentFrame, nsIContent* aContainer)
      : mParentFrame(aParentFrame)
      , mContainer(aContainer)
    {}

    /**
     * The parent frame to use if the inserted children needs to create
     * frame(s).  May be null, which signals that  we shouldn't try to
     * create frames for the inserted children; either because there are
     * no parent frame or because there are multiple insertion points and
     * we will call IssueSingleInsertNofications for each child instead.
     * mContainer should not be used when mParentFrame is null.
     */
    nsContainerFrame* mParentFrame;
    /**
     * The flattened tree parent for the inserted children.
     * It's undefined if mParentFrame is null.
     */
    nsIContent* mContainer;

    /**
     * Whether it is required to insert children one-by-one instead of as a
     * range.
     */
    bool IsMultiple() const;
  };

  /**
   * Checks if the children in the range [aStartChild, aEndChild) can be
   * inserted/appended to one insertion point together.
   *
   * If so, returns that insertion point. If not, returns with
   * InsertionPoint.mFrame == nullptr and issues single ContentInserted calls
   * for each child.
   *
   * aEndChild = nullptr indicates that we are dealing with an append.
   */
  InsertionPoint GetRangeInsertionPoint(nsIContent* aStartChild,
                                        nsIContent* aEndChild,
                                        InsertionKind);

  // Returns true if parent was recreated due to frameset child, false otherwise.
  bool MaybeRecreateForFrameset(nsIFrame* aParentFrame,
                                nsIContent* aStartChild,
                                nsIContent* aEndChild);

  /**
   * For each child in the aStartChild/aEndChild range, calls
   * NoteDirtyDescendantsForServo on their flattened tree parents.  This is
   * used when content is inserted into the document and we decide that
   * we can do lazy frame construction.  It handles children being rebound to
   * different insertion points by calling NoteDirtyDescendantsForServo on each
   * child's flattened tree parent.  Only used when we are styled by Servo.
   */
  void LazilyStyleNewChildRange(nsIContent* aStartChild, nsIContent* aEndChild);

  /**
   * For each child in the aStartChild/aEndChild range, calls StyleNewChildren
   * on their flattened tree parents.  This is used when content is inserted
   * into the document and we decide that we cannot do lazy frame construction.
   * It handles children being rebound to different insertion points by calling
   * StyleNewChildren on each child's flattened tree parent.  Only used when we
   * are styled by Servo.
   */
  void StyleNewChildRange(nsIContent* aStartChild, nsIContent* aEndChild);

public:
  /**
   * Lazy frame construction is controlled by the InsertionKind parameter of
   * nsCSSFrameConstructor::ContentAppended/Inserted. It is true for all
   * inserts/appends as passed from the presshell, except for the insert of the
   * root element, which is always non-lazy.
   *
   * Even if the aInsertionKind passed to ContentAppended/Inserted is
   * Async we still may not be able to construct lazily, so we call
   * MaybeConstructLazily.  MaybeConstructLazily does not allow lazy
   * construction if any of the following are true:
   *  -we are in chrome
   *  -the container is in a native anonymous subtree
   *  -the container is XUL
   *  -is any of the appended/inserted nodes are XUL or editable
   *  -(for inserts) the child is anonymous.  In the append case this function
   *   must not be called with anonymous children.
   * The XUL and chrome checks are because XBL bindings only get applied at
   * frame construction time and some things depend on the bindings getting
   * attached synchronously.
   *
   * If MaybeConstructLazily returns false we construct as usual, but if it
   * returns true then it adds NODE_NEEDS_FRAME bits to the newly
   * inserted/appended nodes and adds NODE_DESCENDANTS_NEED_FRAMES bits to the
   * container and up along the parent chain until it hits the root or another
   * node with that bit set. Then it posts a restyle event to ensure that a
   * flush happens to construct those frames.
   *
   * When the flush happens the presshell calls
   * nsCSSFrameConstructor::CreateNeededFrames. CreateNeededFrames follows any
   * nodes with NODE_DESCENDANTS_NEED_FRAMES set down the content tree looking
   * for nodes with NODE_NEEDS_FRAME set. It calls ContentAppended for any runs
   * of nodes with NODE_NEEDS_FRAME set that are at the end of their childlist,
   * and ContentRangeInserted for any other runs that aren't.
   *
   * If a node is removed from the document then we don't bother unsetting any
   * of the lazy bits that might be set on it, its descendants, or any of its
   * ancestor nodes because that is a slow operation, the work might be wasted
   * if another node gets inserted in its place, and we can clear the bits
   * quicker by processing the content tree from top down the next time we call
   * CreateNeededFrames. (We do clear the bits when BindToTree is called on any
   * nsIContent; so any nodes added to the document will not have any lazy bits
   * set.)
   */

  // If aInsertionKind is Async then frame construction of the new children can
  // be done lazily.
  void ContentAppended(nsIContent* aFirstNewContent, InsertionKind);

  // If aInsertionkind is Async then frame construction of the new child
  // can be done lazily.
  void ContentInserted(nsIContent* aChild,
                       nsILayoutHistoryState* aFrameState,
                       InsertionKind aInsertionKind);

  // Like ContentInserted but handles inserting the children in the range
  // [aStartChild, aEndChild).  aStartChild must be non-null.  aEndChild may be
  // null to indicate the range includes all kids after aStartChild.
  //
  // If aInsertionKind is Async then frame construction of the new children can
  // be done lazily. It is only allowed to be Async when inserting a single
  // node.
  void ContentRangeInserted(nsIContent* aStartChild,
                            nsIContent* aEndChild,
                            nsILayoutHistoryState* aFrameState,
                            InsertionKind aInsertionKind);

  enum RemoveFlags {
    REMOVE_CONTENT,
    REMOVE_FOR_RECONSTRUCTION,
  };

  /**
   * Recreate or destroy frames for aChild.
   *
   * aFlags == REMOVE_CONTENT means aChild has been removed from the document.
   * aFlags == REMOVE_FOR_RECONSTRUCTION means the caller will reconstruct the
   * frames later.
   *
   * In both the above cases, this method will in some cases try to reconstruct
   * frames on some ancestor of aChild.  This can happen regardless of the value
   * of aFlags.
   *
   * The return value indicates whether this "reconstruct an ancestor" action
   * took place.  If true is returned, that means that the frame subtree rooted
   * at some ancestor of aChild's frame was destroyed and will be reconstructed
   * async.
   */
  bool ContentRemoved(nsIContent* aChild,
                      nsIContent* aOldNextSibling,
                      RemoveFlags aFlags);

  void CharacterDataChanged(nsIContent* aContent,
                            const CharacterDataChangeInfo& aInfo);

  // If aContent is a text node that has been optimized away due to being
  // whitespace next to a block boundary (or for some other reason), ensure that
  // a frame for it is created the next time frames are flushed, if it can
  // possibly have a frame at all.
  //
  // Returns whether there are chances for the frame to be unsuppressed.
  bool EnsureFrameForTextNodeIsCreatedAfterFlush(mozilla::dom::CharacterData* aContent);

  // Generate the child frames and process bindings
  void GenerateChildFrames(nsContainerFrame* aFrame);

  // Should be called when a frame is going to be destroyed and
  // WillDestroyFrameTree hasn't been called yet.
  void NotifyDestroyingFrame(nsIFrame* aFrame);

  void RecalcQuotesAndCounters();

  // Called when any counter style is changed.
  void NotifyCounterStylesAreDirty();

  // Gets called when the presshell is destroying itself and also
  // when we tear down our frame tree to reconstruct it
  void WillDestroyFrameTree();

  /**
   * Destroy the frames for aContent.  Note that this may destroy frames
   * for an ancestor instead.
   *
   * Returns whether a reconstruct was posted for any ancestor.
   */
  bool DestroyFramesFor(Element* aElement);

  // Request to create a continuing frame.  This method never returns null.
  nsIFrame* CreateContinuingFrame(nsPresContext*    aPresContext,
                                  nsIFrame*         aFrame,
                                  nsContainerFrame* aParentFrame,
                                  bool              aIsFluid = true);

  // Copy over fixed frames from aParentFrame's prev-in-flow
  nsresult ReplicateFixedFrames(nsPageContentFrame* aParentFrame);

  /**
   * Get the insertion point for aChild.
   */
  InsertionPoint GetInsertionPoint(nsIContent* aChild);

  /**
   * Return the insertion frame of the primary frame of aContent, or its nearest
   * ancestor that isn't display:contents.
   */
  nsContainerFrame* GetContentInsertionFrameFor(nsIContent* aContent);

  // GetInitialContainingBlock() is deprecated in favor of GetRootElementFrame();
  // nsIFrame* GetInitialContainingBlock() { return mRootElementFrame; }
  // This returns the outermost frame for the root element
  nsContainerFrame* GetRootElementFrame() { return mRootElementFrame; }
  // This returns the frame for the root element that does not
  // have a psuedo-element style
  nsIFrame* GetRootElementStyleFrame() { return mRootElementStyleFrame; }
  nsIFrame* GetPageSequenceFrame() { return mPageSequenceFrame; }

  // Get the frame that is the parent of the root element.
  nsContainerFrame* GetDocElementContainingBlock()
    { return mDocElementContainingBlock; }

  void AddSizeOfIncludingThis(nsWindowSizes& aSizes) const;

private:
  struct FrameConstructionItem;
  class FrameConstructionItemList;

  nsContainerFrame* ConstructPageFrame(nsIPresShell*      aPresShell,
                                       nsContainerFrame*  aParentFrame,
                                       nsIFrame*          aPrevPageFrame,
                                       nsContainerFrame*& aCanvasFrame);

  void InitAndRestoreFrame (const nsFrameConstructorState& aState,
                            nsIContent*                    aContent,
                            nsContainerFrame*              aParentFrame,
                            nsIFrame*                      aNewFrame,
                            bool                           aAllowCounters = true);

  already_AddRefed<ComputedStyle> ResolveComputedStyle(nsIContent* aContent);

  // Add the frame construction items for the given aContent and aParentFrame
  // to the list.  This might add more than one item in some rare cases.
  // If aSuppressWhiteSpaceOptimizations is true, optimizations that
  // may suppress the construction of white-space-only text frames
  // must be skipped for these items and items around them.
  void AddFrameConstructionItems(nsFrameConstructorState& aState,
                                 nsIContent*              aContent,
                                 bool                     aSuppressWhiteSpaceOptimizations,
                                 const InsertionPoint&    aInsertion,
                                 FrameConstructionItemList& aItems);

  // Helper method for AddFrameConstructionItems etc.
  // Unsets the need-frame/restyle bits on aContent.
  // return true iff we should attempt to create frames for aContent.
  bool ShouldCreateItemsForChild(nsFrameConstructorState& aState,
                                 nsIContent* aContent,
                                 nsContainerFrame* aParentFrame);

  // Helper method for AddFrameConstructionItems etc.
  // Make sure ShouldCreateItemsForChild() returned true before calling this.
  void DoAddFrameConstructionItems(nsFrameConstructorState& aState,
                                   nsIContent* aContent,
                                   ComputedStyle* aComputedStyle,
                                   bool aSuppressWhiteSpaceOptimizations,
                                   nsContainerFrame* aParentFrame,
                                   FrameConstructionItemList& aItems);

  // Construct the frames for the document element.  This can return null if the
  // document element is display:none, or if the document element has a
  // not-yet-loaded XBL binding, or if it's an SVG element that's not <svg>.
  nsIFrame* ConstructDocElementFrame(Element*                 aDocElement,
                                     nsILayoutHistoryState*   aFrameState);

  // Set up our mDocElementContainingBlock correctly for the given root
  // content.
  void SetUpDocElementContainingBlock(nsIContent* aDocElement);

  /**
   * CreateAttributeContent creates a single content/frame combination for an
   * |attr(foo)| generated content.
   *
   * @param aParentContent the parent content for the generated content (that
   * is, the originating element).
   * @param aParentFrame the parent frame for the generated frame
   * @param aAttrNamespace the namespace of the attribute in question
   * @param aAttrName the localname of the attribute
   * @param aComputedStyle the style to use
   * @param aGeneratedContent the array of generated content to append the
   *                          created content to.
   * @param [out] aNewContent the content node we create
   * @param [out] aNewFrame the new frame we create
   */
  void CreateAttributeContent(const Element& aParentContent,
                              nsIFrame* aParentFrame,
                              int32_t aAttrNamespace,
                              nsAtom* aAttrName,
                              ComputedStyle* aComputedStyle,
                              nsCOMArray<nsIContent>& aGeneratedContent,
                              nsIContent** aNewContent,
                              nsIFrame** aNewFrame);

  /**
   * Create a text node containing the given string. If aText is non-null
   * then we also set aText to the returned node.
   */
  already_AddRefed<nsIContent> CreateGenConTextNode(nsFrameConstructorState& aState,
                                                    const nsString& aString,
                                                    RefPtr<nsTextNode>* aText,
                                                    nsGenConInitializer* aInitializer);

  /**
   * Create a content node for the given generated content style.
   * The caller takes care of making it SetIsNativeAnonymousRoot, binding it
   * to the document, and creating frames for it.
   * @param aOriginatingElement is the node that has the before/after style.
   * @param aComputedStyle is the 'before' or 'after' pseudo-element style.
   * @param aContentIndex is the index of the content item to create
   */
  already_AddRefed<nsIContent> CreateGeneratedContent(nsFrameConstructorState& aState,
                                                      const Element& aOriginatingElement,
                                                      ComputedStyle& aComputedStyle,
                                                      uint32_t aContentIndex);

  // aParentFrame may be null; this method doesn't use it directly in any case.
  void CreateGeneratedContentItem(nsFrameConstructorState& aState,
                                  nsContainerFrame* aParentFrame,
                                  Element& aOriginatingElement,
                                  ComputedStyle&,
                                  CSSPseudoElementType aPseudoElement,
                                  FrameConstructionItemList& aItems);

  // This method can change aFrameList: it can chop off the beginning and put
  // it in aParentFrame while putting the remainder into a ib-split sibling of
  // aParentFrame.  aPrevSibling must be the frame after which aFrameList is to
  // be placed on aParentFrame's principal child list.  It may be null if
  // aFrameList is being added at the beginning of the child list.
  void AppendFramesToParent(nsFrameConstructorState&       aState,
                            nsContainerFrame*              aParentFrame,
                            nsFrameItems&                  aFrameList,
                            nsIFrame*                      aPrevSibling,
                            bool                           aIsRecursiveCall = false);

  // BEGIN TABLE SECTION
  /**
   * Construct a table wrapper frame. This is the FrameConstructionData
   * callback used for the job.
   */
  nsIFrame* ConstructTable(nsFrameConstructorState& aState,
                           FrameConstructionItem&   aItem,
                           nsContainerFrame*        aParentFrame,
                           const nsStyleDisplay*    aDisplay,
                           nsFrameItems&            aFrameItems);

  /**
   * FrameConstructionData callback for constructing table rows and row groups.
   */
  nsIFrame* ConstructTableRowOrRowGroup(nsFrameConstructorState& aState,
                                        FrameConstructionItem&   aItem,
                                        nsContainerFrame*        aParentFrame,
                                        const nsStyleDisplay*    aStyleDisplay,
                                        nsFrameItems&            aFrameItems);

  /**
   * FrameConstructionData callback used for constructing table columns.
   */
  nsIFrame* ConstructTableCol(nsFrameConstructorState& aState,
                              FrameConstructionItem&   aItem,
                              nsContainerFrame*        aParentFrame,
                              const nsStyleDisplay*    aStyleDisplay,
                              nsFrameItems&            aFrameItems);

  /**
   * FrameConstructionData callback used for constructing table cells.
   */
  nsIFrame* ConstructTableCell(nsFrameConstructorState& aState,
                               FrameConstructionItem&   aItem,
                               nsContainerFrame*        aParentFrame,
                               const nsStyleDisplay*    aStyleDisplay,
                               nsFrameItems&            aFrameItems);

private:
  /* An enum of possible parent types for anonymous table or ruby object
     construction */
  enum ParentType {
    eTypeBlock = 0, /* This includes all non-table-related frames */
    eTypeRow,
    eTypeRowGroup,
    eTypeColGroup,
    eTypeTable,
    eTypeRuby,
    eTypeRubyBase,
    eTypeRubyBaseContainer,
    eTypeRubyText,
    eTypeRubyTextContainer,
    eParentTypeCount
  };

  /* 4 bits is enough to handle our ParentType values */
#define FCDATA_PARENT_TYPE_OFFSET 28
  /* Macro to get the desired parent type out of an mBits member of
     FrameConstructionData */
#define FCDATA_DESIRED_PARENT_TYPE(_bits)           \
  ParentType((_bits) >> FCDATA_PARENT_TYPE_OFFSET)
  /* Macro to create FrameConstructionData bits out of a desired parent type */
#define FCDATA_DESIRED_PARENT_TYPE_TO_BITS(_type)     \
  (((uint32_t)(_type)) << FCDATA_PARENT_TYPE_OFFSET)

  /* Get the parent type that aParentFrame has. */
  static ParentType GetParentType(nsIFrame* aParentFrame) {
    return GetParentType(aParentFrame->Type());
  }

  /* Get the parent type for the given LayoutFrameType */
  static ParentType GetParentType(mozilla::LayoutFrameType aFrameType);

  static bool IsRubyParentType(ParentType aParentType) {
    return (aParentType == eTypeRuby ||
            aParentType == eTypeRubyBase ||
            aParentType == eTypeRubyBaseContainer ||
            aParentType == eTypeRubyText ||
            aParentType == eTypeRubyTextContainer);
  }

  static bool IsTableParentType(ParentType aParentType) {
    return (aParentType == eTypeTable ||
            aParentType == eTypeRow ||
            aParentType == eTypeRowGroup ||
            aParentType == eTypeColGroup);
  }

  /* A constructor function that just creates an nsIFrame object.  The caller
     is responsible for initializing the object, adding it to frame lists,
     constructing frames for the children, etc.

     @param nsIPresShell the presshell whose arena should be used to allocate
                         the frame.
     @param ComputedStyle the style to use for the frame. */
  typedef nsIFrame* (* FrameCreationFunc)(nsIPresShell*, ComputedStyle*);
  typedef nsContainerFrame* (* ContainerFrameCreationFunc)(nsIPresShell*, ComputedStyle*);
  typedef nsBlockFrame* (* BlockFrameCreationFunc)(nsIPresShell*, ComputedStyle*);

  /* A function that can be used to get a FrameConstructionData.  Such
     a function is allowed to return null.

     @param nsIContent the node for which the frame is being constructed.
     @param ComputedStyle the style to be used for the frame.
  */
  struct FrameConstructionData;
  typedef const FrameConstructionData*
    (* FrameConstructionDataGetter)(const Element&, ComputedStyle&);

  /* A constructor function that's used for complicated construction tasks.
     This is expected to create the new frame, initialize it, add whatever
     needs to be added to aFrameItems (XXXbz is that really necessary?  Could
     caller add?  Might there be cases when the returned frame or its
     placeholder is not the thing that ends up in aFrameItems?  If not, would
     it be safe to do the add into the frame construction state after
     processing kids?  Look into this as a followup!), process children as
     needed, etc.  It is NOT expected to deal with setting the frame on the
     content.

     @param aState the frame construction state to use.
     @param aItem the frame construction item to use
     @param aParentFrame the frame to set as the parent of the
                         newly-constructed frame.
     @param aStyleDisplay the display struct from aItem's mComputedStyle
     @param aFrameItems the frame list to add the new frame (or its
                        placeholder) to.
     @return the frame that was constructed.  This frame is what the caller
             will set as the frame on the content.  Guaranteed non-null.
  */
  typedef nsIFrame*
    (nsCSSFrameConstructor::* FrameFullConstructor)(nsFrameConstructorState& aState,
                                                    FrameConstructionItem& aItem,
                                                    nsContainerFrame* aParentFrame,
                                                    const nsStyleDisplay* aStyleDisplay,
                                                    nsFrameItems& aFrameItems);

  /* Bits that modify the way a FrameConstructionData is handled */

  /* If the FCDATA_SKIP_FRAMESET bit is set, then the frame created should not
     be set as the primary frame on the content node.  This should only be used
     in very rare cases when we create more than one frame for a given content
     node. */
#define FCDATA_SKIP_FRAMESET 0x1
  /* If the FCDATA_FUNC_IS_DATA_GETTER bit is set, then the mFunc of the
     FrameConstructionData is a getter function that can be used to get the
     actual FrameConstructionData to use. */
#define FCDATA_FUNC_IS_DATA_GETTER 0x2
  /* If the FCDATA_FUNC_IS_FULL_CTOR bit is set, then the FrameConstructionData
     has an mFullConstructor.  In this case, there is no relevant mData or
     mFunc */
#define FCDATA_FUNC_IS_FULL_CTOR 0x4
  /* If FCDATA_DISALLOW_OUT_OF_FLOW is set, do not allow the frame to
     float or be absolutely positioned.  This can also be used with
     FCDATA_FUNC_IS_FULL_CTOR to indicate what the full-constructor
     function will do. */
#define FCDATA_DISALLOW_OUT_OF_FLOW 0x8
  /* If FCDATA_FORCE_NULL_ABSPOS_CONTAINER is set, make sure to push a
     null absolute containing block before processing children for this
     frame.  If this is not set, the frame will be pushed as the
     absolute containing block as needed, based on its style */
#define FCDATA_FORCE_NULL_ABSPOS_CONTAINER 0x10
  /* If FCDATA_WRAP_KIDS_IN_BLOCKS is set, the inline kids of the frame
     will be wrapped in blocks.  This is only usable for MathML at the
     moment. */
#define FCDATA_WRAP_KIDS_IN_BLOCKS 0x20
  /* If FCDATA_SUPPRESS_FRAME is set, no frame should be created for the
     content.  If this bit is set, nothing else in the struct needs to be
     set. */
#define FCDATA_SUPPRESS_FRAME 0x40
  /* If FCDATA_MAY_NEED_SCROLLFRAME is set, the new frame should be wrapped in
     a scrollframe if its overflow type so requires. */
#define FCDATA_MAY_NEED_SCROLLFRAME 0x80
#ifdef MOZ_XUL
  /* If FCDATA_IS_POPUP is set, the new frame is a XUL popup frame.  These need
     some really weird special handling.  */
#define FCDATA_IS_POPUP 0x100
#endif /* MOZ_XUL */
  /* If FCDATA_SKIP_ABSPOS_PUSH is set, don't push this frame as an
     absolute containing block, no matter what its style says. */
#define FCDATA_SKIP_ABSPOS_PUSH 0x200
  /* If FCDATA_DISALLOW_GENERATED_CONTENT is set, then don't allow generated
     content when processing kids of this frame.  This should not be used with
     FCDATA_FUNC_IS_FULL_CTOR */
#define FCDATA_DISALLOW_GENERATED_CONTENT 0x400
  /* If FCDATA_IS_TABLE_PART is set, then the frame is some sort of
     table-related thing and we should not attempt to fetch a table-cell parent
     for it if it's inside another table-related frame. */
#define FCDATA_IS_TABLE_PART 0x800
  /* If FCDATA_IS_INLINE is set, then the frame is a non-replaced CSS
     inline box. */
#define FCDATA_IS_INLINE 0x1000
  /* If FCDATA_IS_LINE_PARTICIPANT is set, the frame is something that will
     return true for IsFrameOfType(nsIFrame::eLineParticipant) */
#define FCDATA_IS_LINE_PARTICIPANT 0x2000
  /* If FCDATA_IS_LINE_BREAK is set, the frame is something that will
     induce a line break boundary before and after itself. */
#define FCDATA_IS_LINE_BREAK 0x4000
  /* If FCDATA_ALLOW_BLOCK_STYLES is set, allow block styles when processing
     children of a block (i.e. allow ::first-letter/line).
     This should not be used with FCDATA_FUNC_IS_FULL_CTOR. */
#define FCDATA_ALLOW_BLOCK_STYLES 0x8000
  /* If FCDATA_USE_CHILD_ITEMS is set, then use the mChildItems in the relevant
     FrameConstructionItem instead of trying to process the content's children.
     This can be used with or without FCDATA_FUNC_IS_FULL_CTOR.
     The child items might still need table pseudo processing. */
#define FCDATA_USE_CHILD_ITEMS 0x10000
  /* If FCDATA_FORCED_NON_SCROLLABLE_BLOCK is set, then this block
     would have been scrollable but has been forced to be
     non-scrollable due to being in a paginated context. */
#define FCDATA_FORCED_NON_SCROLLABLE_BLOCK 0x20000
  /* If FCDATA_CREATE_BLOCK_WRAPPER_FOR_ALL_KIDS is set, then create a
     block formatting context wrapper around the kids of this frame
     using the FrameConstructionData's mPseudoAtom for its anonymous
     box type. */
#define FCDATA_CREATE_BLOCK_WRAPPER_FOR_ALL_KIDS 0x40000
  /* If FCDATA_IS_SVG_TEXT is set, then this text frame is a descendant of
     an SVG text frame. */
#define FCDATA_IS_SVG_TEXT 0x80000
  /**
   * When FCDATA_CREATE_BLOCK_WRAPPER_FOR_ALL_KIDS is set, this bit says
   * if we should create a grid/flex/columnset container instead of
   * a block wrapper when the styles says so.
   */
#define FCDATA_ALLOW_GRID_FLEX_COLUMNSET 0x200000
  /**
   * Whether the kids of this FrameConstructionData should be flagged as having
   * a wrapper anon box parent.  This should only be set if
   * FCDATA_USE_CHILD_ITEMS is set.
   */
#define FCDATA_IS_WRAPPER_ANON_BOX 0x400000
  /**
   * If FCDATA_MAY_NEED_BULLET is set, then the frame will be checked
   * whether an nsBulletFrame needs to be created for it or not. Only the
   * frames inherited from nsBlockFrame should have this bit set.
   */
#define FCDATA_MAY_NEED_BULLET 0x800000

  /* Structure representing information about how a frame should be
     constructed.  */
  struct FrameConstructionData {
    // Flag bits that can modify the way the construction happens
    uint32_t mBits;
    // We have exactly one of three types of functions, so use a union for
    // better cache locality for the ones that aren't pointer-to-member.  That
    // one needs to be separate, because we can't cast between it and the
    // others and hence wouldn't be able to initialize the union without a
    // constructor and all the resulting generated code.  See documentation
    // above for FrameCreationFunc, FrameConstructionDataGetter, and
    // FrameFullConstructor to see what the functions would do.
    union Func {
      FrameCreationFunc mCreationFunc;
      FrameConstructionDataGetter mDataGetter;
    } mFunc;
    FrameFullConstructor mFullConstructor;
    // For cases when FCDATA_CREATE_BLOCK_WRAPPER_FOR_ALL_KIDS is set, the
    // anonymous box type to use for that wrapper.
    nsCSSAnonBoxPseudoStaticAtom* const mAnonBoxPseudo;
  };

  /* Structure representing a mapping of an atom to a FrameConstructionData.
     This can be used with non-static atoms, assuming that the nsAtom* is
     stored somewhere that this struct can point to (that is, a static
     nsAtom*) and that it's allocated before the struct is ever used. */
  struct FrameConstructionDataByTag {
    const nsStaticAtom* const mTag;
    const FrameConstructionData mData;
  };

  /* Structure representing a mapping of an integer to a
     FrameConstructionData. There are no magic integer values here. */
  struct FrameConstructionDataByInt {
    /* Could be used for display or whatever else */
    const int32_t mInt;
    const FrameConstructionData mData;
  };

  struct FrameConstructionDataByDisplay {
#ifdef DEBUG
    const mozilla::StyleDisplay mDisplay;
#endif
    const FrameConstructionData mData;
  };

#ifdef DEBUG
#define FCDATA_FOR_DISPLAY(_display, _fcdata) \
  { _display, _fcdata }
#else
#define FCDATA_FOR_DISPLAY(_display, _fcdata) \
  { _fcdata }
#endif

  /* Structure that has a FrameConstructionData and style pseudo-type
     for a table pseudo-frame */
  struct PseudoParentData {
    const FrameConstructionData mFCData;
    nsCSSAnonBoxPseudoStaticAtom* const mPseudoType;
  };
  /* Array of such structures that we use to properly construct table
     pseudo-frames as needed */
  static const PseudoParentData sPseudoParentData[eParentTypeCount];

  // The information that concerns the frame constructor after loading an XBL
  // binding.
  //
  // This is expected to just be used temporarily to aggregate the different
  // objects that LoadXBLBindingIfNeeded returns.
  struct MOZ_STACK_CLASS XBLBindingLoadInfo
  {
    RefPtr<ComputedStyle> mStyle;
    mozilla::UniquePtr<PendingBinding> mPendingBinding;
    nsAtom* mTag = nullptr;

    // For the 'no binding loaded' case.
    XBLBindingLoadInfo(nsIContent&, ComputedStyle&);

    // For the case we actually load an XBL binding.
    XBLBindingLoadInfo(already_AddRefed<ComputedStyle>&& aStyle,
                       mozilla::UniquePtr<PendingBinding> aPendingBinding,
                       nsAtom* aTag);

    // For the error case.
    XBLBindingLoadInfo();
  };

  // Returns null mStyle / mTag members to signal an error.
  XBLBindingLoadInfo LoadXBLBindingIfNeeded(nsIContent&,
                                            ComputedStyle&,
                                            uint32_t aFlags);

  const FrameConstructionData* FindDataForContent(nsIContent&,
                                                  ComputedStyle&,
                                                  nsIFrame* aParentFrame,
                                                  nsAtom* aTag,
                                                  uint32_t aFlags);

  // aParentFrame might be null.  If it is, that means it was an inline frame.
  static const FrameConstructionData* FindTextData(const Text&,
                                                   nsIFrame* aParentFrame);
  const FrameConstructionData* FindElementData(const Element&,
                                               ComputedStyle&,
                                               nsIFrame* aParentFrame,
                                               nsAtom* aTag,
                                               uint32_t aFlags);
  const FrameConstructionData* FindElementTagData(const Element&,
                                                  ComputedStyle&,
                                                  nsIFrame* aParentFrame,
                                                  nsAtom* aTag,
                                                  uint32_t aFlags);

  /* A function that takes an integer, content, style, and array of
     FrameConstructionDataByInts and finds the appropriate frame construction
     data to use and returns it.  This can return null if none of the integers
     match or if the matching integer has a FrameConstructionDataGetter that
     returns null. */
  static const FrameConstructionData*
    FindDataByInt(int32_t aInt,
                  const Element&,
                  ComputedStyle&,
                  const FrameConstructionDataByInt* aDataPtr,
                  uint32_t aDataLength);

  /**
   * A function that takes a tag, content, style, and array of
   * FrameConstructionDataByTags and finds the appropriate frame construction
   * data to use and returns it.
   *
   * This can return null if none of the tags match or if the matching tag has a
   * FrameConstructionDataGetter that returns null. In the case that the tags
   * actually match, aTagFound will be true, even if the return value is null.
   */
  static const FrameConstructionData*
    FindDataByTag(nsAtom* aTag,
                  const Element& aElement,
                  ComputedStyle& aComputedStyle,
                  const FrameConstructionDataByTag* aDataPtr,
                  uint32_t aDataLength);

  /* A class representing a list of FrameConstructionItems.  Instances of this
     class are only created as AutoFrameConstructionItemList, or as a member
     of FrameConstructionItem. */
  class FrameConstructionItemList
  {
  public:
    void Reset(nsCSSFrameConstructor* aFCtor)
    {
      Destroy(aFCtor);
      this->~FrameConstructionItemList();
      new (this) FrameConstructionItemList();
    }

    void SetLineBoundaryAtStart(bool aBoundary) { mLineBoundaryAtStart = aBoundary; }
    void SetLineBoundaryAtEnd(bool aBoundary) { mLineBoundaryAtEnd = aBoundary; }
    void SetParentHasNoXBLChildren(bool aHasNoXBLChildren) {
      mParentHasNoXBLChildren = aHasNoXBLChildren;
    }
    bool HasLineBoundaryAtStart() { return mLineBoundaryAtStart; }
    bool HasLineBoundaryAtEnd() { return mLineBoundaryAtEnd; }
    bool ParentHasNoXBLChildren() { return mParentHasNoXBLChildren; }
    bool IsEmpty() const { return mItems.isEmpty(); }
    bool AnyItemsNeedBlockParent() const { return mLineParticipantCount != 0; }
    bool AreAllItemsInline() const { return mInlineCount == mItemCount; }
    bool AreAllItemsBlock() const { return mBlockCount == mItemCount; }
    bool AllWantParentType(ParentType aDesiredParentType) const {
      return mDesiredParentCounts[aDesiredParentType] == mItemCount;
    }

    // aSuppressWhiteSpaceOptimizations is true if optimizations that
    // skip constructing whitespace frames for this item or items
    // around it cannot be performed.
    // Also, the return value is always non-null, thanks to infallible 'new'.
    FrameConstructionItem* AppendItem(nsCSSFrameConstructor*