Source/WebCore/rendering/style/RenderStyle.cpp

/*
 * Copyright (C) 1999 Antti Koivisto (koivisto@kde.org)
 * Copyright (C) 2004-2015 Apple Inc. All rights reserved.
 * Copyright (C) 2011 Adobe Systems Incorporated. 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.
 *
 */

#include "config.h"
#include "RenderStyle.h"

#include "ContentData.h"
#include "CSSCustomPropertyValue.h"
#include "CSSParser.h"
#include "CSSPropertyNames.h"
#include "CursorList.h"
#include "FloatRoundedRect.h"
#include "FontCascade.h"
#include "FontSelector.h"
#include "InlineTextBoxStyle.h"
#include "Pagination.h"
#include "QuotesData.h"
#include "RenderObject.h"
#include "RenderTheme.h"
#include "RuntimeEnabledFeatures.h"
#include "ScaleTransformOperation.h"
#include "ShadowData.h"
#include "StyleImage.h"
#include "StyleInheritedData.h"
#include "StyleResolver.h"
#include "StyleScrollSnapPoints.h"
#include "StyleSelfAlignmentData.h"
#include "StyleTreeResolver.h"
#include "WillChangeData.h"
#include <wtf/MathExtras.h>
#include <wtf/PointerComparison.h>
#include <wtf/StdLibExtras.h>
#include <algorithm>

#if ENABLE(TEXT_AUTOSIZING)
#include <wtf/text/StringHash.h>
#endif

namespace WebCore {

struct SameSizeAsBorderValue {
    float m_width;
    Color m_color;
    int m_restBits;
};

COMPILE_ASSERT(sizeof(BorderValue) == sizeof(SameSizeAsBorderValue), BorderValue_should_not_grow);

struct SameSizeAsRenderStyle {
    void* dataRefs[7];
    void* ownPtrs[1];
    void* dataRefSvgStyle;
    struct InheritedFlags {
        unsigned m_bitfields[2];
    } inherited_flags;

    struct NonInheritedFlags {
        uint64_t m_flags;
    } noninherited_flags;
#if !ASSERT_DISABLED || ENABLE(SECURITY_ASSERTIONS)
    bool deletionCheck;
#endif
};

COMPILE_ASSERT(sizeof(RenderStyle) == sizeof(SameSizeAsRenderStyle), RenderStyle_should_stay_small);

RenderStyle& RenderStyle::defaultStyle()
{
    static RenderStyle& style = *new RenderStyle(CreateDefaultStyle);
    return style;
}

RenderStyle RenderStyle::create()
{
    return clone(defaultStyle());
}

std::unique_ptr<RenderStyle> RenderStyle::createPtr()
{
    return clonePtr(defaultStyle());
}

RenderStyle RenderStyle::clone(const RenderStyle& style)
{
    return RenderStyle(style, Clone);
}

std::unique_ptr<RenderStyle> RenderStyle::clonePtr(const RenderStyle& style)
{
    return std::make_unique<RenderStyle>(style, Clone);
}

RenderStyle RenderStyle::createAnonymousStyleWithDisplay(const RenderStyle& parentStyle, EDisplay display)
{
    auto newStyle = create();
    newStyle.inheritFrom(parentStyle);
    newStyle.inheritUnicodeBidiFrom(&parentStyle);
    newStyle.setDisplay(display);
    return newStyle;
}

RenderStyle RenderStyle::createStyleInheritingFromPseudoStyle(const RenderStyle& pseudoStyle)
{
    ASSERT(pseudoStyle.styleType() == BEFORE || pseudoStyle.styleType() == AFTER);

    auto style = create();
    style.inheritFrom(pseudoStyle);
    return style;
}

RenderStyle::RenderStyle(CreateDefaultStyleTag)
    : m_box(StyleBoxData::create())
    , visual(StyleVisualData::create())
    , m_background(StyleBackgroundData::create())
    , surround(StyleSurroundData::create())
    , rareNonInheritedData(StyleRareNonInheritedData::create())
    , rareInheritedData(StyleRareInheritedData::create())
    , inherited(StyleInheritedData::create())
    , m_svgStyle(SVGRenderStyle::create())
{
    inherited_flags._empty_cells = initialEmptyCells();
    inherited_flags._caption_side = initialCaptionSide();
    inherited_flags._list_style_type = initialListStyleType();
    inherited_flags._list_style_position = initialListStylePosition();
    inherited_flags._visibility = initialVisibility();
    inherited_flags._text_align = initialTextAlign();
    inherited_flags._text_transform = initialTextTransform();
    inherited_flags._text_decorations = initialTextDecoration();
    inherited_flags._cursor_style = initialCursor();
#if ENABLE(CURSOR_VISIBILITY)
    inherited_flags.m_cursorVisibility = initialCursorVisibility();
#endif
    inherited_flags._direction = initialDirection();
    inherited_flags._white_space = initialWhiteSpace();
    inherited_flags._border_collapse = initialBorderCollapse();
    inherited_flags.m_rtlOrdering = initialRTLOrdering();
    inherited_flags._box_direction = initialBoxDirection();
    inherited_flags.m_printColorAdjust = initialPrintColorAdjust();
    inherited_flags._pointerEvents = initialPointerEvents();
    inherited_flags._insideLink = NotInsideLink;
    inherited_flags._insideDefaultButton = false;
    inherited_flags.m_writingMode = initialWritingMode();

    static_assert((sizeof(InheritedFlags) <= 8), "InheritedFlags does not grow");
    static_assert((sizeof(NonInheritedFlags) <= 8), "NonInheritedFlags does not grow");
}

RenderStyle::RenderStyle(const RenderStyle& other, CloneTag)
    : m_box(other.m_box)
    , visual(other.visual)
    , m_background(other.m_background)
    , surround(other.surround)
    , rareNonInheritedData(other.rareNonInheritedData)
    , rareInheritedData(other.rareInheritedData)
    , inherited(other.inherited)
    , m_svgStyle(other.m_svgStyle)
    , inherited_flags(other.inherited_flags)
    , noninherited_flags(other.noninherited_flags)
{
}

RenderStyle::~RenderStyle()
{
#if !ASSERT_DISABLED || ENABLE(SECURITY_ASSERTIONS)
    ASSERT_WITH_SECURITY_IMPLICATION(!m_deletionHasBegun);
    m_deletionHasBegun = true;
#endif
}

bool RenderStyle::isCSSGridLayoutEnabled()
{
#if ENABLE(CSS_GRID_LAYOUT)
    return RuntimeEnabledFeatures::sharedFeatures().isCSSGridLayoutEnabled();
#else
    return false;
#endif
}

static StyleSelfAlignmentData resolvedSelfAlignment(const StyleSelfAlignmentData& value, ItemPosition normalValueBehavior)
{
    ASSERT(value.position() != ItemPositionAuto);
    if (value.position() == ItemPositionNormal)
        return { normalValueBehavior, OverflowAlignmentDefault };
    return value;
}

StyleSelfAlignmentData RenderStyle::resolvedAlignItems(ItemPosition normalValueBehaviour) const
{
    return resolvedSelfAlignment(alignItems(), normalValueBehaviour);
}

StyleSelfAlignmentData RenderStyle::resolvedAlignSelf(const RenderStyle& parentStyle, ItemPosition normalValueBehaviour) const
{
    // The auto keyword computes to the parent's align-items computed value.
    // We will return the behaviour of 'normal' value if needed, which is specific of each layout model.
    if (alignSelfPosition() == ItemPositionAuto)
        return parentStyle.resolvedAlignItems(normalValueBehaviour);
    return resolvedSelfAlignment(alignSelf(), normalValueBehaviour);
}

StyleSelfAlignmentData RenderStyle::resolvedJustifyItems(ItemPosition normalValueBehaviour) const
{
    // FIXME: justify-items 'auto' value is allowed only to provide the 'legacy' keyword's behavior, which it's still not implemented for layout.
    // "If the inherited value of justify-items includes the legacy keyword, auto computes to the inherited value."
    // https://drafts.csswg.org/css-align/#justify-items-property
    if (justifyItemsPosition() == ItemPositionAuto)
        return { normalValueBehaviour, OverflowAlignmentDefault };

    return resolvedSelfAlignment(justifyItems(), normalValueBehaviour);
}

StyleSelfAlignmentData RenderStyle::resolvedJustifySelf(const RenderStyle& parentStyle, ItemPosition normalValueBehaviour) const
{
    // The auto keyword computes to the parent's justify-items computed value.
    // We will return the behaviour of 'normal' value if needed, which is specific of each layout model.
    if (justifySelfPosition() == ItemPositionAuto)
        return parentStyle.resolvedJustifyItems(normalValueBehaviour);
    return resolvedSelfAlignment(justifySelf(), normalValueBehaviour);
}

static inline ContentPosition resolvedContentAlignmentPosition(const StyleContentAlignmentData& value, const StyleContentAlignmentData& normalValueBehavior)
{
    return (value.position() == ContentPositionNormal && value.distribution() == ContentDistributionDefault) ? normalValueBehavior.position() : value.position();
}

static inline ContentDistributionType resolvedContentAlignmentDistribution(const StyleContentAlignmentData& value, const StyleContentAlignmentData& normalValueBehavior)
{
    return (value.position() == ContentPositionNormal && value.distribution() == ContentDistributionDefault) ? normalValueBehavior.distribution() : value.distribution();
}

ContentPosition RenderStyle::resolvedJustifyContentPosition(const StyleContentAlignmentData& normalValueBehavior) const
{
    return resolvedContentAlignmentPosition(justifyContent(), normalValueBehavior);
}

ContentDistributionType RenderStyle::resolvedJustifyContentDistribution(const StyleContentAlignmentData& normalValueBehavior) const
{
    return resolvedContentAlignmentDistribution(justifyContent(), normalValueBehavior);
}

ContentPosition RenderStyle::resolvedAlignContentPosition(const StyleContentAlignmentData& normalValueBehavior) const
{
    return resolvedContentAlignmentPosition(alignContent(), normalValueBehavior);
}

ContentDistributionType RenderStyle::resolvedAlignContentDistribution(const StyleContentAlignmentData& normalValueBehavior) const
{
    return resolvedContentAlignmentDistribution(alignContent(), normalValueBehavior);
}

void RenderStyle::inheritFrom(const RenderStyle& inheritParent)
{
    rareInheritedData = inheritParent.rareInheritedData;
    inherited = inheritParent.inherited;
    inherited_flags = inheritParent.inherited_flags;

    if (m_svgStyle != inheritParent.m_svgStyle)
        m_svgStyle.access()->inheritFrom(inheritParent.m_svgStyle.get());
}

void RenderStyle::copyNonInheritedFrom(const RenderStyle* other)
{
    m_box = other->m_box;
    visual = other->visual;
    m_background = other->m_background;
    surround = other->surround;
    rareNonInheritedData = other->rareNonInheritedData;
    noninherited_flags.copyNonInheritedFrom(other->noninherited_flags);

    if (m_svgStyle != other->m_svgStyle)
        m_svgStyle.access()->copyNonInheritedFrom(other->m_svgStyle.get());

    ASSERT(zoom() == initialZoom());
}

bool RenderStyle::operator==(const RenderStyle& o) const
{
    // compare everything except the pseudoStyle pointer
    return inherited_flags == o.inherited_flags
        && noninherited_flags == o.noninherited_flags
        && m_box == o.m_box
        && visual == o.visual
        && m_background == o.m_background
        && surround == o.surround
        && rareNonInheritedData == o.rareNonInheritedData
        && rareInheritedData == o.rareInheritedData
        && inherited == o.inherited
        && m_svgStyle == o.m_svgStyle
            ;
}

bool RenderStyle::hasUniquePseudoStyle() const
{
    if (!m_cachedPseudoStyles || styleType() != NOPSEUDO)
        return false;

    for (size_t i = 0; i < m_cachedPseudoStyles->size(); ++i) {
        RenderStyle* pseudoStyle = m_cachedPseudoStyles->at(i).get();
        if (pseudoStyle->unique())
            return true;
    }

    return false;
}

RenderStyle* RenderStyle::getCachedPseudoStyle(PseudoId pid) const
{
    if (!m_cachedPseudoStyles || !m_cachedPseudoStyles->size())
        return nullptr;

    if (styleType() != NOPSEUDO) 
        return nullptr;

    for (size_t i = 0; i < m_cachedPseudoStyles->size(); ++i) {
        RenderStyle* pseudoStyle = m_cachedPseudoStyles->at(i).get();
        if (pseudoStyle->styleType() == pid)
            return pseudoStyle;
    }

    return nullptr;
}

RenderStyle* RenderStyle::addCachedPseudoStyle(std::unique_ptr<RenderStyle> pseudo)
{
    if (!pseudo)
        return nullptr;

    ASSERT(pseudo->styleType() > NOPSEUDO);

    RenderStyle* result = pseudo.get();

    if (!m_cachedPseudoStyles)
        m_cachedPseudoStyles = std::make_unique<PseudoStyleCache>();

    m_cachedPseudoStyles->append(WTFMove(pseudo));

    return result;
}

void RenderStyle::removeCachedPseudoStyle(PseudoId pid)
{
    if (!m_cachedPseudoStyles)
        return;
    for (size_t i = 0; i < m_cachedPseudoStyles->size(); ++i) {
        RenderStyle* pseudoStyle = m_cachedPseudoStyles->at(i).get();
        if (pseudoStyle->styleType() == pid) {
            m_cachedPseudoStyles->remove(i);
            return;
        }
    }
}

bool RenderStyle::inheritedNotEqual(const RenderStyle* other) const
{
    return inherited_flags != other->inherited_flags
           || inherited != other->inherited
           || m_svgStyle->inheritedNotEqual(other->m_svgStyle.get())
           || rareInheritedData != other->rareInheritedData;
}

#if ENABLE(TEXT_AUTOSIZING)

static inline unsigned computeFontHash(const FontCascade& font)
{
    IntegerHasher hasher;
    hasher.add(ASCIICaseInsensitiveHash::hash(font.fontDescription().firstFamily()));
    hasher.add(font.fontDescription().specifiedSize());
    return hasher.hash();
}

unsigned RenderStyle::hashForTextAutosizing() const
{
    // FIXME: Not a very smart hash. Could be improved upon. See <https://bugs.webkit.org/show_bug.cgi?id=121131>.
    unsigned hash = rareNonInheritedData->m_appearance;
    hash ^= rareNonInheritedData->marginBeforeCollapse;
    hash ^= rareNonInheritedData->marginAfterCollapse;
    hash ^= rareNonInheritedData->lineClamp.value();
    hash ^= rareInheritedData->overflowWrap;
    hash ^= rareInheritedData->nbspMode;
    hash ^= rareInheritedData->lineBreak;
    hash ^= WTF::FloatHash<float>::hash(inherited->specifiedLineHeight.value());
    hash ^= computeFontHash(inherited->fontCascade);
    hash ^= WTF::FloatHash<float>::hash(inherited->horizontal_border_spacing);
    hash ^= WTF::FloatHash<float>::hash(inherited->vertical_border_spacing);
    hash ^= inherited_flags._box_direction;
    hash ^= inherited_flags.m_rtlOrdering;
    hash ^= noninherited_flags.position();
    hash ^= noninherited_flags.floating();
    hash ^= rareNonInheritedData->textOverflow;
    hash ^= rareInheritedData->textSecurity;
    return hash;
}

bool RenderStyle::equalForTextAutosizing(const RenderStyle& other) const
{
    return rareNonInheritedData->m_appearance == other.rareNonInheritedData->m_appearance
        && rareNonInheritedData->marginBeforeCollapse == other.rareNonInheritedData->marginBeforeCollapse
        && rareNonInheritedData->marginAfterCollapse == other.rareNonInheritedData->marginAfterCollapse
        && rareNonInheritedData->lineClamp == other.rareNonInheritedData->lineClamp
        && rareInheritedData->textSizeAdjust == other.rareInheritedData->textSizeAdjust
        && rareInheritedData->overflowWrap == other.rareInheritedData->overflowWrap
        && rareInheritedData->nbspMode == other.rareInheritedData->nbspMode
        && rareInheritedData->lineBreak == other.rareInheritedData->lineBreak
        && rareInheritedData->textSecurity == other.rareInheritedData->textSecurity
        && inherited->specifiedLineHeight == other.inherited->specifiedLineHeight
        && inherited->fontCascade.equalForTextAutoSizing(other.inherited->fontCascade)
        && inherited->horizontal_border_spacing == other.inherited->horizontal_border_spacing
        && inherited->vertical_border_spacing == other.inherited->vertical_border_spacing
        && inherited_flags._box_direction == other.inherited_flags._box_direction
        && inherited_flags.m_rtlOrdering == other.inherited_flags.m_rtlOrdering
        && noninherited_flags.position() == other.noninherited_flags.position()
        && noninherited_flags.floating() == other.noninherited_flags.floating()
        && rareNonInheritedData->textOverflow == other.rareNonInheritedData->textOverflow;
}

#endif // ENABLE(TEXT_AUTOSIZING)

bool RenderStyle::inheritedDataShared(const RenderStyle* other) const
{
    // This is a fast check that only looks if the data structures are shared.
    return inherited_flags == other->inherited_flags
        && inherited.get() == other->inherited.get()
        && m_svgStyle.get() == other->m_svgStyle.get()
        && rareInheritedData.get() == other->rareInheritedData.get();
}

static bool positionChangeIsMovementOnly(const LengthBox& a, const LengthBox& b, const Length& width)
{
    // If any unit types are different, then we can't guarantee
    // that this was just a movement.
    if (a.left().type() != b.left().type()
        || a.right().type() != b.right().type()
        || a.top().type() != b.top().type()
        || a.bottom().type() != b.bottom().type())
        return false;

    // Only one unit can be non-auto in the horizontal direction and
    // in the vertical direction.  Otherwise the adjustment of values
    // is changing the size of the box.
    if (!a.left().isIntrinsicOrAuto() && !a.right().isIntrinsicOrAuto())
        return false;
    if (!a.top().isIntrinsicOrAuto() && !a.bottom().isIntrinsicOrAuto())
        return false;
    // If our width is auto and left or right is specified then this 
    // is not just a movement - we need to resize to our container.
    if ((!a.left().isIntrinsicOrAuto() || !a.right().isIntrinsicOrAuto()) && width.isIntrinsicOrAuto())
        return false;

    // One of the units is fixed or percent in both directions and stayed
    // that way in the new style.  Therefore all we are doing is moving.
    return true;
}

inline bool RenderStyle::changeAffectsVisualOverflow(const RenderStyle& other) const
{
    if (rareNonInheritedData.get() != other.rareNonInheritedData.get()
        && !arePointingToEqualData(rareNonInheritedData->m_boxShadow, other.rareNonInheritedData->m_boxShadow))
        return true;

    if (rareInheritedData.get() != other.rareInheritedData.get()
        && !arePointingToEqualData(rareInheritedData->textShadow, other.rareInheritedData->textShadow))
        return true;

    if (inherited_flags._text_decorations != other.inherited_flags._text_decorations
        || visual->textDecoration != other.visual->textDecoration
        || rareNonInheritedData->m_textDecorationStyle != other.rareNonInheritedData->m_textDecorationStyle) {
        // Underlines are always drawn outside of their textbox bounds when text-underline-position: under;
        // is specified. We can take an early out here.
        if (textUnderlinePosition() == TextUnderlinePositionUnder
            || other.textUnderlinePosition() == TextUnderlinePositionUnder)
            return true;
        return visualOverflowForDecorations(*this, nullptr) != visualOverflowForDecorations(other, nullptr);
    }

    if (hasOutlineInVisualOverflow() != other.hasOutlineInVisualOverflow())
        return true;
    return false;
}

bool RenderStyle::changeRequiresLayout(const RenderStyle& other, unsigned& changedContextSensitiveProperties) const
{
    if (m_box->width() != other.m_box->width()
        || m_box->minWidth() != other.m_box->minWidth()
        || m_box->maxWidth() != other.m_box->maxWidth()
        || m_box->height() != other.m_box->height()
        || m_box->minHeight() != other.m_box->minHeight()
        || m_box->maxHeight() != other.m_box->maxHeight())
        return true;

    if (m_box->verticalAlign() != other.m_box->verticalAlign() || noninherited_flags.verticalAlign() != other.noninherited_flags.verticalAlign())
        return true;

    if (m_box->boxSizing() != other.m_box->boxSizing())
        return true;

    if (surround->margin != other.surround->margin)
        return true;

    if (surround->padding != other.surround->padding)
        return true;

    // FIXME: We should add an optimized form of layout that just recomputes visual overflow.
    if (changeAffectsVisualOverflow(other))
        return true;

    if (rareNonInheritedData.get() != other.rareNonInheritedData.get()) {
        if (rareNonInheritedData->m_appearance != other.rareNonInheritedData->m_appearance
            || rareNonInheritedData->marginBeforeCollapse != other.rareNonInheritedData->marginBeforeCollapse
            || rareNonInheritedData->marginAfterCollapse != other.rareNonInheritedData->marginAfterCollapse
            || rareNonInheritedData->lineClamp != other.rareNonInheritedData->lineClamp
            || rareNonInheritedData->m_initialLetter != other.rareNonInheritedData->m_initialLetter
            || rareNonInheritedData->textOverflow != other.rareNonInheritedData->textOverflow)
            return true;

        if (rareNonInheritedData->m_regionFragment != other.rareNonInheritedData->m_regionFragment)
            return true;

        if (rareNonInheritedData->m_shapeMargin != other.rareNonInheritedData->m_shapeMargin)
            return true;

        if (rareNonInheritedData->m_deprecatedFlexibleBox != other.rareNonInheritedData->m_deprecatedFlexibleBox)
            return true;

        if (rareNonInheritedData->m_flexibleBox != other.rareNonInheritedData->m_flexibleBox)
            return true;

        if (rareNonInheritedData->m_order != other.rareNonInheritedData->m_order
            || rareNonInheritedData->m_alignContent != other.rareNonInheritedData->m_alignContent
            || rareNonInheritedData->m_alignItems != other.rareNonInheritedData->m_alignItems
            || rareNonInheritedData->m_alignSelf != other.rareNonInheritedData->m_alignSelf
            || rareNonInheritedData->m_justifyContent != other.rareNonInheritedData->m_justifyContent
            || rareNonInheritedData->m_justifyItems != other.rareNonInheritedData->m_justifyItems
            || rareNonInheritedData->m_justifySelf != other.rareNonInheritedData->m_justifySelf)
            return true;

        if (!arePointingToEqualData(rareNonInheritedData->m_boxReflect, other.rareNonInheritedData->m_boxReflect))
            return true;

        if (rareNonInheritedData->m_multiCol != other.rareNonInheritedData->m_multiCol)
            return true;

        if (rareNonInheritedData->m_transform != other.rareNonInheritedData->m_transform) {
            if (rareNonInheritedData->m_transform->hasTransform() != other.rareNonInheritedData->m_transform->hasTransform())
                return true;
            if (*rareNonInheritedData->m_transform != *other.rareNonInheritedData->m_transform) {
                changedContextSensitiveProperties |= ContextSensitivePropertyTransform;
                // Don't return; keep looking for another change
            }
        }

#if ENABLE(CSS_GRID_LAYOUT)
        if (rareNonInheritedData->m_grid != other.rareNonInheritedData->m_grid
            || rareNonInheritedData->m_gridItem != other.rareNonInheritedData->m_gridItem)
            return true;
#endif

#if ENABLE(DASHBOARD_SUPPORT)
        // If regions change, trigger a relayout to re-calc regions.
        if (rareNonInheritedData->m_dashboardRegions != other.rareNonInheritedData->m_dashboardRegions)
            return true;
#endif

        if (!arePointingToEqualData(rareNonInheritedData->m_willChange, other.rareNonInheritedData->m_willChange)) {
            changedContextSensitiveProperties |= ContextSensitivePropertyWillChange;
            // Don't return; keep looking for another change
        }
    }

    if (rareInheritedData.get() != other.rareInheritedData.get()) {
        if (rareInheritedData->indent != other.rareInheritedData->indent
#if ENABLE(CSS3_TEXT)
            || rareInheritedData->m_textAlignLast != other.rareInheritedData->m_textAlignLast
            || rareInheritedData->m_textJustify != other.rareInheritedData->m_textJustify
            || rareInheritedData->m_textIndentLine != other.rareInheritedData->m_textIndentLine
#endif
            || rareInheritedData->m_effectiveZoom != other.rareInheritedData->m_effectiveZoom
            || rareInheritedData->m_textZoom != other.rareInheritedData->m_textZoom
#if ENABLE(TEXT_AUTOSIZING)
            || rareInheritedData->textSizeAdjust != other.rareInheritedData->textSizeAdjust
#endif
            || rareInheritedData->wordBreak != other.rareInheritedData->wordBreak
            || rareInheritedData->overflowWrap != other.rareInheritedData->overflowWrap
            || rareInheritedData->nbspMode != other.rareInheritedData->nbspMode
            || rareInheritedData->lineBreak != other.rareInheritedData->lineBreak
            || rareInheritedData->textSecurity != other.rareInheritedData->textSecurity
            || rareInheritedData->hyphens != other.rareInheritedData->hyphens
            || rareInheritedData->hyphenationLimitBefore != other.rareInheritedData->hyphenationLimitBefore
            || rareInheritedData->hyphenationLimitAfter != other.rareInheritedData->hyphenationLimitAfter
            || rareInheritedData->hyphenationString != other.rareInheritedData->hyphenationString
            || rareInheritedData->m_rubyPosition != other.rareInheritedData->m_rubyPosition
            || rareInheritedData->textEmphasisMark != other.rareInheritedData->textEmphasisMark
            || rareInheritedData->textEmphasisPosition != other.rareInheritedData->textEmphasisPosition
            || rareInheritedData->textEmphasisCustomMark != other.rareInheritedData->textEmphasisCustomMark
            || rareInheritedData->m_textOrientation != other.rareInheritedData->m_textOrientation
            || rareInheritedData->m_tabSize != other.rareInheritedData->m_tabSize
            || rareInheritedData->m_lineBoxContain != other.rareInheritedData->m_lineBoxContain
            || rareInheritedData->m_lineGrid != other.rareInheritedData->m_lineGrid
#if ENABLE(CSS_IMAGE_ORIENTATION)
            || rareInheritedData->m_imageOrientation != other.rareInheritedData->m_imageOrientation
#endif
#if ENABLE(CSS_IMAGE_RESOLUTION)
            || rareInheritedData->m_imageResolutionSource != other.rareInheritedData->m_imageResolutionSource
            || rareInheritedData->m_imageResolutionSnap != other.rareInheritedData->m_imageResolutionSnap
            || rareInheritedData->m_imageResolution != other.rareInheritedData->m_imageResolution
#endif
            || rareInheritedData->m_lineSnap != other.rareInheritedData->m_lineSnap
            || rareInheritedData->m_lineAlign != other.rareInheritedData->m_lineAlign
            || rareInheritedData->m_hangingPunctuation != other.rareInheritedData->m_hangingPunctuation
#if ENABLE(ACCELERATED_OVERFLOW_SCROLLING)
            || rareInheritedData->useTouchOverflowScrolling != other.rareInheritedData->useTouchOverflowScrolling
#endif
            || rareInheritedData->listStyleImage != other.rareInheritedData->listStyleImage) // FIXME: needs arePointingToEqualData()?
            return true;

        if (textStrokeWidth() != other.textStrokeWidth())
            return true;
    }

    if (inherited->line_height != other.inherited->line_height
#if ENABLE(TEXT_AUTOSIZING)
        || inherited->specifiedLineHeight != other.inherited->specifiedLineHeight
#endif
        || inherited->fontCascade != other.inherited->fontCascade
        || inherited->horizontal_border_spacing != other.inherited->horizontal_border_spacing
        || inherited->vertical_border_spacing != other.inherited->vertical_border_spacing
        || inherited_flags._box_direction != other.inherited_flags._box_direction
        || inherited_flags.m_rtlOrdering != other.inherited_flags.m_rtlOrdering
        || noninherited_flags.position() != other.noninherited_flags.position()
        || noninherited_flags.floating() != other.noninherited_flags.floating()
        || noninherited_flags.originalDisplay() != other.noninherited_flags.originalDisplay())
        return true;


    if ((noninherited_flags.effectiveDisplay()) >= TABLE) {
        if (inherited_flags._border_collapse != other.inherited_flags._border_collapse
            || inherited_flags._empty_cells != other.inherited_flags._empty_cells
            || inherited_flags._caption_side != other.inherited_flags._caption_side
            || noninherited_flags.tableLayout() != other.noninherited_flags.tableLayout())
            return true;

        // In the collapsing border model, 'hidden' suppresses other borders, while 'none'
        // does not, so these style differences can be width differences.
        if (inherited_flags._border_collapse
            && ((borderTopStyle() == BHIDDEN && other.borderTopStyle() == BNONE)
                || (borderTopStyle() == BNONE && other.borderTopStyle() == BHIDDEN)
                || (borderBottomStyle() == BHIDDEN && other.borderBottomStyle() == BNONE)
                || (borderBottomStyle() == BNONE && other.borderBottomStyle() == BHIDDEN)
                || (borderLeftStyle() == BHIDDEN && other.borderLeftStyle() == BNONE)
                || (borderLeftStyle() == BNONE && other.borderLeftStyle() == BHIDDEN)
                || (borderRightStyle() == BHIDDEN && other.borderRightStyle() == BNONE)
                || (borderRightStyle() == BNONE && other.borderRightStyle() == BHIDDEN)))
            return true;
    }

    if (noninherited_flags.effectiveDisplay() == LIST_ITEM) {
        if (inherited_flags._list_style_type != other.inherited_flags._list_style_type
            || inherited_flags._list_style_position != other.inherited_flags._list_style_position)
            return true;
    }

    if (inherited_flags._text_align != other.inherited_flags._text_align
        || inherited_flags._text_transform != other.inherited_flags._text_transform
        || inherited_flags._direction != other.inherited_flags._direction
        || inherited_flags._white_space != other.inherited_flags._white_space
        || noninherited_flags.clear() != other.noninherited_flags.clear()
        || noninherited_flags.unicodeBidi() != other.noninherited_flags.unicodeBidi())
        return true;

    // Check block flow direction.
    if (inherited_flags.m_writingMode != other.inherited_flags.m_writingMode)
        return true;

    // Check text combine mode.
    if (rareNonInheritedData->m_textCombine != other.rareNonInheritedData->m_textCombine)
        return true;

    // Check breaks.
    if (rareNonInheritedData->m_breakBefore != other.rareNonInheritedData->m_breakBefore
        || rareNonInheritedData->m_breakAfter != other.rareNonInheritedData->m_breakAfter
        || rareNonInheritedData->m_breakInside != other.rareNonInheritedData->m_breakInside)
        return true;

    // Overflow returns a layout hint.
    if (noninherited_flags.overflowX() != other.noninherited_flags.overflowX()
        || noninherited_flags.overflowY() != other.noninherited_flags.overflowY())
        return true;

    // If our border widths change, then we need to layout.  Other changes to borders
    // only necessitate a repaint.
    if (borderLeftWidth() != other.borderLeftWidth()
        || borderTopWidth() != other.borderTopWidth()
        || borderBottomWidth() != other.borderBottomWidth()
        || borderRightWidth() != other.borderRightWidth())
        return true;

    // If the counter directives change, trigger a relayout to re-calculate counter values and rebuild the counter node tree.
    if (!arePointingToEqualData(rareNonInheritedData->m_counterDirectives, other.rareNonInheritedData->m_counterDirectives))
        return true;

    if ((visibility() == COLLAPSE) != (other.visibility() == COLLAPSE))
        return true;

    if (rareNonInheritedData->hasOpacity() != other.rareNonInheritedData->hasOpacity()) {
        // FIXME: We would like to use SimplifiedLayout here, but we can't quite do that yet.
        // We need to make sure SimplifiedLayout can operate correctly on RenderInlines (we will need
        // to add a selfNeedsSimplifiedLayout bit in order to not get confused and taint every line).
        // In addition we need to solve the floating object issue when layers come and go. Right now
        // a full layout is necessary to keep floating object lists sane.
        return true;
    }

    if (rareNonInheritedData->hasFilters() != other.rareNonInheritedData->hasFilters())
        return true;

#if ENABLE(FILTERS_LEVEL_2)
    if (rareNonInheritedData->hasBackdropFilters() != other.rareNonInheritedData->hasBackdropFilters())
        return true;
#endif

    if (!arePointingToEqualData(rareInheritedData->quotes, other.rareInheritedData->quotes))
        return true;

    if (position() != StaticPosition) {
        if (surround->offset != other.surround->offset) {
            // FIXME: We would like to use SimplifiedLayout for relative positioning, but we can't quite do that yet.
            // We need to make sure SimplifiedLayout can operate correctly on RenderInlines (we will need
            // to add a selfNeedsSimplifiedLayout bit in order to not get confused and taint every line).
            if (position() != AbsolutePosition)
                return true;

            // Optimize for the case where a positioned layer is moving but not changing size.
            if (!positionChangeIsMovementOnly(surround->offset, other.surround->offset, m_box->width()))
                return true;
        }
    }

    bool hasFirstLineStyle = hasPseudoStyle(FIRST_LINE);
    if (hasFirstLineStyle != other.hasPseudoStyle(FIRST_LINE))
        return true;
    if (hasFirstLineStyle) {
        auto* firstLineStyle = getCachedPseudoStyle(FIRST_LINE);
        if (!firstLineStyle)
            return true;
        auto* otherFirstLineStyle = other.getCachedPseudoStyle(FIRST_LINE);
        if (!otherFirstLineStyle)
            return true;
        // FIXME: Not all first line style changes actually need layout.
        if (*firstLineStyle != *otherFirstLineStyle)
            return true;
    }

    return false;
}

bool RenderStyle::changeRequiresPositionedLayoutOnly(const RenderStyle& other, unsigned&) const
{
    if (position() == StaticPosition)
        return false;

    if (surround->offset != other.surround->offset) {
        // Optimize for the case where a positioned layer is moving but not changing size.
        if (position() == AbsolutePosition && positionChangeIsMovementOnly(surround->offset, other.surround->offset, m_box->width()))
            return true;
    }
    
    return false;
}

bool RenderStyle::changeRequiresLayerRepaint(const RenderStyle& other, unsigned& changedContextSensitiveProperties) const
{
    // StyleResolver has ensured that zIndex is non-auto only if it's applicable.
    if (m_box->zIndex() != other.m_box->zIndex() || m_box->hasAutoZIndex() != other.m_box->hasAutoZIndex())
        return true;

    if (position() != StaticPosition) {
        if (visual->clip != other.visual->clip || visual->hasClip != other.visual->hasClip) {
            changedContextSensitiveProperties |= ContextSensitivePropertyClipRect;
            return true;
        }
    }

#if ENABLE(CSS_COMPOSITING)
    if (rareNonInheritedData->m_effectiveBlendMode != other.rareNonInheritedData->m_effectiveBlendMode)
        return true;
#endif

    if (rareNonInheritedData->m_opacity != other.rareNonInheritedData->m_opacity) {
        changedContextSensitiveProperties |= ContextSensitivePropertyOpacity;
        // Don't return; keep looking for another change.
    }

    if (rareNonInheritedData->m_filter != other.rareNonInheritedData->m_filter) {
        changedContextSensitiveProperties |= ContextSensitivePropertyFilter;
        // Don't return; keep looking for another change.
    }

#if ENABLE(FILTERS_LEVEL_2)
    if (rareNonInheritedData->m_backdropFilter != other.rareNonInheritedData->m_backdropFilter) {
        changedContextSensitiveProperties |= ContextSensitivePropertyFilter;
        // Don't return; keep looking for another change.
    }
#endif

    if (rareNonInheritedData->m_mask != other.rareNonInheritedData->m_mask
        || rareNonInheritedData->m_maskBoxImage != other.rareNonInheritedData->m_maskBoxImage)
        return true;

    return false;
}

bool RenderStyle::changeRequiresRepaint(const RenderStyle& other, unsigned& changedContextSensitiveProperties) const
{
    if (inherited_flags._visibility != other.inherited_flags._visibility
        || inherited_flags.m_printColorAdjust != other.inherited_flags.m_printColorAdjust
        || inherited_flags._insideLink != other.inherited_flags._insideLink
        || inherited_flags._insideDefaultButton != other.inherited_flags._insideDefaultButton
        || surround->border != other.surround->border
        || !m_background->isEquivalentForPainting(*other.m_background)
        || rareInheritedData->userModify != other.rareInheritedData->userModify
        || rareInheritedData->userSelect != other.rareInheritedData->userSelect
        || rareNonInheritedData->userDrag != other.rareNonInheritedData->userDrag
        || rareNonInheritedData->m_borderFit != other.rareNonInheritedData->m_borderFit
        || rareNonInheritedData->m_objectFit != other.rareNonInheritedData->m_objectFit
        || rareNonInheritedData->m_objectPosition != other.rareNonInheritedData->m_objectPosition
        || rareInheritedData->m_imageRendering != other.rareInheritedData->m_imageRendering)
        return true;

    if (rareNonInheritedData->m_shapeOutside != other.rareNonInheritedData->m_shapeOutside)
        return true;

    // FIXME: this should probably be moved to changeRequiresLayerRepaint().
    if (rareNonInheritedData->m_clipPath != other.rareNonInheritedData->m_clipPath) {
        changedContextSensitiveProperties |= ContextSensitivePropertyClipPath;
        // Don't return; keep looking for another change.
    }

    return false;
}

bool RenderStyle::changeRequiresRepaintIfTextOrBorderOrOutline(const RenderStyle& other, unsigned&) const
{
    if (inherited->color != other.inherited->color
        || inherited_flags._text_decorations != other.inherited_flags._text_decorations
        || visual->textDecoration != other.visual->textDecoration
        || rareNonInheritedData->m_textDecorationStyle != other.rareNonInheritedData->m_textDecorationStyle
        || rareNonInheritedData->m_textDecorationColor != other.rareNonInheritedData->m_textDecorationColor
        || rareInheritedData->m_textDecorationSkip != other.rareInheritedData->m_textDecorationSkip
        || rareInheritedData->textFillColor != other.rareInheritedData->textFillColor
        || rareInheritedData->textStrokeColor != other.rareInheritedData->textStrokeColor
        || rareInheritedData->textEmphasisColor != other.rareInheritedData->textEmphasisColor
        || rareInheritedData->textEmphasisFill != other.rareInheritedData->textEmphasisFill)
        return true;

    return false;
}

bool RenderStyle::changeRequiresRecompositeLayer(const RenderStyle& other, unsigned&) const
{
    if (rareNonInheritedData.get() != other.rareNonInheritedData.get()) {
        if (rareNonInheritedData->m_transformStyle3D != other.rareNonInheritedData->m_transformStyle3D
            || rareNonInheritedData->m_backfaceVisibility != other.rareNonInheritedData->m_backfaceVisibility
            || rareNonInheritedData->m_perspective != other.rareNonInheritedData->m_perspective
            || rareNonInheritedData->m_perspectiveOriginX != other.rareNonInheritedData->m_perspectiveOriginX
            || rareNonInheritedData->m_perspectiveOriginY != other.rareNonInheritedData->m_perspectiveOriginY)
            return true;
    }

    return false;
}

StyleDifference RenderStyle::diff(const RenderStyle& other, unsigned& changedContextSensitiveProperties) const
{
    changedContextSensitiveProperties = ContextSensitivePropertyNone;

    StyleDifference svgChange = StyleDifferenceEqual;
    if (m_svgStyle != other.m_svgStyle) {
        svgChange = m_svgStyle->diff(other.m_svgStyle.get());
        if (svgChange == StyleDifferenceLayout)
            return svgChange;
    }

    if (changeRequiresLayout(other, changedContextSensitiveProperties))
        return StyleDifferenceLayout;

    // SVGRenderStyle::diff() might have returned StyleDifferenceRepaint, eg. if fill changes.
    // If eg. the font-size changed at the same time, we're not allowed to return StyleDifferenceRepaint,
    // but have to return StyleDifferenceLayout, that's why  this if branch comes after all branches
    // that are relevant for SVG and might return StyleDifferenceLayout.
    if (svgChange != StyleDifferenceEqual)
        return svgChange;

    if (changeRequiresPositionedLayoutOnly(other, changedContextSensitiveProperties))
        return StyleDifferenceLayoutPositionedMovementOnly;

    if (changeRequiresLayerRepaint(other, changedContextSensitiveProperties))
        return StyleDifferenceRepaintLayer;

    if (changeRequiresRepaint(other, changedContextSensitiveProperties))
        return StyleDifferenceRepaint;

    if (changeRequiresRecompositeLayer(other, changedContextSensitiveProperties))
        return StyleDifferenceRecompositeLayer;

    if (changeRequiresRepaintIfTextOrBorderOrOutline(other, changedContextSensitiveProperties))
        return StyleDifferenceRepaintIfTextOrBorderOrOutline;

    // Cursors are not checked, since they will be set appropriately in response to mouse events,
    // so they don't need to cause any repaint or layout.

    // Animations don't need to be checked either.  We always set the new style on the RenderObject, so we will get a chance to fire off
    // the resulting transition properly.
    return StyleDifferenceEqual;
}

bool RenderStyle::diffRequiresLayerRepaint(const RenderStyle& style, bool isComposited) const
{
    unsigned changedContextSensitiveProperties = 0;

    if (changeRequiresRepaint(style, changedContextSensitiveProperties))
        return true;

    if (isComposited && changeRequiresLayerRepaint(style, changedContextSensitiveProperties))
        return changedContextSensitiveProperties & ContextSensitivePropertyClipRect;

    return false;
}

void RenderStyle::setClip(Length top, Length right, Length bottom, Length left)
{
    StyleVisualData* data = visual.access();
    data->clip.top() = top;
    data->clip.right() = right;
    data->clip.bottom() = bottom;
    data->clip.left() = left;
}

void RenderStyle::addCursor(RefPtr<StyleImage>&& image, const IntPoint& hotSpot)
{
    if (!rareInheritedData.access()->cursorData)
        rareInheritedData.access()->cursorData = CursorList::create();
    rareInheritedData.access()->cursorData->append(CursorData(WTFMove(image), hotSpot));
}

void RenderStyle::setCursorList(RefPtr<CursorList>&& list)
{
    rareInheritedData.access()->cursorData = WTFMove(list);
}

void RenderStyle::setQuotes(RefPtr<QuotesData>&& q)
{
    if (rareInheritedData->quotes == q || (rareInheritedData->quotes && q && *rareInheritedData->quotes == *q))
        return;

    rareInheritedData.access()->quotes = WTFMove(q);
}

void RenderStyle::setWillChange(RefPtr<WillChangeData>&& willChangeData)
{
    if (arePointingToEqualData(rareNonInheritedData->m_willChange.get(), willChangeData.get()))
        return;

    rareNonInheritedData.access()->m_willChange = WTFMove(willChangeData);
}

void RenderStyle::clearCursorList()
{
    if (rareInheritedData->cursorData)
        rareInheritedData.access()->cursorData = nullptr;
}

void RenderStyle::clearContent()
{
    if (rareNonInheritedData->m_content)
        rareNonInheritedData.access()->m_content = nullptr;
}

void RenderStyle::appendContent(std::unique_ptr<ContentData> contentData)
{
    auto& content = rareNonInheritedData.access()->m_content;
    ContentData* lastContent = content.get();
    while (lastContent && lastContent->next())
        lastContent = lastContent->next();

    if (lastContent)
        lastContent->setNext(WTFMove(contentData));
    else
        content = WTFMove(contentData);
}

void RenderStyle::setContent(RefPtr<StyleImage>&& image, bool add)
{
    if (!image)
        return;
        
    if (add) {
        appendContent(std::make_unique<ImageContentData>(image.releaseNonNull()));
        return;
    }

    rareNonInheritedData.access()->m_content = std::make_unique<ImageContentData>(image.releaseNonNull());
    if (!rareNonInheritedData.access()->m_altText.isNull())
        rareNonInheritedData.access()->m_content->setAltText(rareNonInheritedData.access()->m_altText);
}

void RenderStyle::setContent(const String& string, bool add)
{
    auto& content = rareNonInheritedData.access()->m_content;
    if (add) {
        ContentData* lastContent = content.get();
        while (lastContent && lastContent->next())
            lastContent = lastContent->next();

        if (lastContent) {
            // We attempt to merge with the last ContentData if possible.
            if (is<TextContentData>(*lastContent)) {
                TextContentData& textContent = downcast<TextContentData>(*lastContent);
                textContent.setText(textContent.text() + string);
            } else
                lastContent->setNext(std::make_unique<TextContentData>(string));

            if (!rareNonInheritedData.access()->m_altText.isNull())
                lastContent->setAltText(rareNonInheritedData.access()->m_altText);
            return;
        }
    }

    content = std::make_unique<TextContentData>(string);
    if (!rareNonInheritedData.access()->m_altText.isNull())
        content->setAltText(rareNonInheritedData.access()->m_altText);
}

void RenderStyle::setContent(std::unique_ptr<CounterContent> counter, bool add)
{
    if (!counter)
        return;

    if (add) {
        appendContent(std::make_unique<CounterContentData>(WTFMove(counter)));
        return;
    }

    rareNonInheritedData.access()->m_content = std::make_unique<CounterContentData>(WTFMove(counter));
}

void RenderStyle::setContent(QuoteType quote, bool add)
{
    if (add) {
        appendContent(std::make_unique<QuoteContentData>(quote));
        return;
    }

    rareNonInheritedData.access()->m_content = std::make_unique<QuoteContentData>(quote);
}

void RenderStyle::setContentAltText(const String& string)
{
    rareNonInheritedData.access()->m_altText = string;
    
    if (rareNonInheritedData.access()->m_content)
        rareNonInheritedData.access()->m_content->setAltText(string);
}

const String& RenderStyle::contentAltText() const
{
    return rareNonInheritedData->m_altText;
}

void RenderStyle::setHasAttrContent()
{
    setUnique();
    SET_VAR(rareNonInheritedData, m_hasAttrContent, true);
}

// FIXME: use affectedByTransformOrigin().
static inline bool requireTransformOrigin(const Vector<RefPtr<TransformOperation>>& transformOperations, RenderStyle::ApplyTransformOrigin applyOrigin)
{
    // transform-origin brackets the transform with translate operations.
    // Optimize for the case where the only transform is a translation, since the transform-origin is irrelevant
    // in that case.
    if (applyOrigin != RenderStyle::IncludeTransformOrigin)
        return false;

    for (auto& operation : transformOperations) {
        TransformOperation::OperationType type = operation->type();
        if (type != TransformOperation::TRANSLATE_X
            && type != TransformOperation::TRANSLATE_Y
            && type != TransformOperation::TRANSLATE 
            && type != TransformOperation::TRANSLATE_Z
            && type != TransformOperation::TRANSLATE_3D)
            return true;
    }

    return false;
}

void RenderStyle::applyTransform(TransformationMatrix& transform, const FloatRect& boundingBox, ApplyTransformOrigin applyOrigin) const
{
    auto& operations = rareNonInheritedData->m_transform->m_operations.operations();
    bool applyTransformOrigin = requireTransformOrigin(operations, applyOrigin);

    float offsetX = transformOriginX().isPercent() ? boundingBox.x() : 0;
    float offsetY = transformOriginY().isPercent() ? boundingBox.y() : 0;

    if (applyTransformOrigin) {
        transform.translate3d(floatValueForLength(transformOriginX(), boundingBox.width()) + offsetX,
                              floatValueForLength(transformOriginY(), boundingBox.height()) + offsetY,
                              transformOriginZ());
    }

    for (auto& operation : operations)
        operation->apply(transform, boundingBox.size());

    if (applyTransformOrigin) {
        transform.translate3d(-floatValueForLength(transformOriginX(), boundingBox.width()) - offsetX,
                              -floatValueForLength(transformOriginY(), boundingBox.height()) - offsetY,
                              -transformOriginZ());
    }
}

void RenderStyle::setPageScaleTransform(float scale)
{
    if (scale == 1)
        return;
    TransformOperations transform;
    transform.operations().append(ScaleTransformOperation::create(scale, scale, ScaleTransformOperation::SCALE));
    setTransform(transform);
    setTransformOriginX(Length(0, Fixed));
    setTransformOriginY(Length(0, Fixed));
}

void RenderStyle::setTextShadow(std::unique_ptr<ShadowData> shadowData, bool add)
{
    ASSERT(!shadowData || (!shadowData->spread() && shadowData->style() == Normal));

    StyleRareInheritedData* rareData = rareInheritedData.access();
    if (!add) {
        rareData->textShadow = WTFMove(shadowData);
        return;
    }

    shadowData->setNext(WTFMove(rareData->textShadow));
    rareData->textShadow = WTFMove(shadowData);
}

void RenderStyle::setBoxShadow(std::unique_ptr<ShadowData> shadowData, bool add)
{
    StyleRareNonInheritedData* rareData = rareNonInheritedData.access();
    if (!add) {
        rareData->m_boxShadow = WTFMove(shadowData);
        return;
    }

    shadowData->setNext(WTFMove(rareData->m_boxShadow));
    rareData->m_boxShadow = WTFMove(shadowData);
}

static RoundedRect::Radii calcRadiiFor(const BorderData& border, const LayoutSize& size)
{
    return RoundedRect::Radii(
        LayoutSize(valueForLength(border.topLeft().width(), size.width()),
            valueForLength(border.topLeft().height(), size.height())),
        LayoutSize(valueForLength(border.topRight().width(), size.width()),
            valueForLength(border.topRight().height(), size.height())),
        LayoutSize(valueForLength(border.bottomLeft().width(), size.width()),
            valueForLength(border.bottomLeft().height(), size.height())),
        LayoutSize(valueForLength(border.bottomRight().width(), size.width()),
            valueForLength(border.bottomRight().height(), size.height())));
}

StyleImage* RenderStyle::listStyleImage() const { return rareInheritedData->listStyleImage.get(); }
void RenderStyle::setListStyleImage(RefPtr<StyleImage>&& v)
{
    if (rareInheritedData->listStyleImage != v)
        rareInheritedData.access()->listStyleImage = WTFMove(v);
}

const Color& RenderStyle::color() const
{
    return inherited->color;
}

const Color& RenderStyle::visitedLinkColor() const
{
    return inherited->visitedLinkColor;
}

void RenderStyle::setColor(const Color& v)
{
    SET_VAR(inherited, color, v);
}

void RenderStyle::setVisitedLinkColor(const Color& v)
{
    SET_VAR(inherited, visitedLinkColor, v);
}

float RenderStyle::horizontalBorderSpacing() const { return inherited->horizontal_border_spacing; }
float RenderStyle::verticalBorderSpacing() const { return inherited->vertical_border_spacing; }
void RenderStyle::setHorizontalBorderSpacing(float v) { SET_VAR(inherited, horizontal_border_spacing, v); }
void RenderStyle::setVerticalBorderSpacing(float v) { SET_VAR(inherited, vertical_border_spacing, v); }

RoundedRect RenderStyle::getRoundedBorderFor(const LayoutRect& borderRect, bool includeLogicalLeftEdge, bool includeLogicalRightEdge) const
{
    RoundedRect roundedRect(borderRect);
    if (hasBorderRadius()) {
        RoundedRect::Radii radii = calcRadiiFor(surround->border, borderRect.size());
        radii.scale(calcBorderRadiiConstraintScaleFor(borderRect, radii));
        roundedRect.includeLogicalEdges(radii, isHorizontalWritingMode(), includeLogicalLeftEdge, includeLogicalRightEdge);
    }
    return roundedRect;
}

RoundedRect RenderStyle::getRoundedInnerBorderFor(const LayoutRect& borderRect, bool includeLogicalLeftEdge, bool includeLogicalRightEdge) const
{
    bool horizontal = isHorizontalWritingMode();

    LayoutUnit leftWidth = (!horizontal || includeLogicalLeftEdge) ? borderLeftWidth() : 0;
    LayoutUnit rightWidth = (!horizontal || includeLogicalRightEdge) ? borderRightWidth() : 0;
    LayoutUnit topWidth = (horizontal || includeLogicalLeftEdge) ? borderTopWidth() : 0;
    LayoutUnit bottomWidth = (horizontal || includeLogicalRightEdge) ? borderBottomWidth() : 0;

    return getRoundedInnerBorderFor(borderRect, topWidth, bottomWidth, leftWidth, rightWidth, includeLogicalLeftEdge, includeLogicalRightEdge);
}

RoundedRect RenderStyle::getRoundedInnerBorderFor(const LayoutRect& borderRect, LayoutUnit topWidth, LayoutUnit bottomWidth,
    LayoutUnit leftWidth, LayoutUnit rightWidth, bool includeLogicalLeftEdge, bool includeLogicalRightEdge) const
{
    LayoutRect innerRect(borderRect.x() + leftWidth, 
               borderRect.y() + topWidth, 
               borderRect.width() - leftWidth - rightWidth, 
               borderRect.height() - topWidth - bottomWidth);

    RoundedRect roundedRect(innerRect);

    if (hasBorderRadius()) {
        RoundedRect::Radii radii = getRoundedBorderFor(borderRect).radii();
        radii.shrink(topWidth, bottomWidth, leftWidth, rightWidth);
        roundedRect.includeLogicalEdges(radii, isHorizontalWritingMode(), includeLogicalLeftEdge, includeLogicalRightEdge);
    }
    return roundedRect;
}

static bool allLayersAreFixed(const FillLayer* layer)
{
    bool allFixed = true;
    
    for (const FillLayer* currLayer = layer; currLayer; currLayer = currLayer->next())
        allFixed &= (currLayer->image() && currLayer->attachment() == FixedBackgroundAttachment);

    return layer && allFixed;
}

bool RenderStyle::hasEntirelyFixedBackground() const
{
    return allLayersAreFixed(backgroundLayers());
}

const CounterDirectiveMap* RenderStyle::counterDirectives() const
{
    return rareNonInheritedData->m_counterDirectives.get();
}

CounterDirectiveMap& RenderStyle::accessCounterDirectives()
{
    auto& map = rareNonInheritedData.access()->m_counterDirectives;
    if (!map)
        map = std::make_unique<CounterDirectiveMap>();
    return *map;
}

const CounterDirectives RenderStyle::getCounterDirectives(const AtomicString& identifier) const
{
    if (const CounterDirectiveMap* directives = counterDirectives())
        return directives->get(identifier);
    return CounterDirectives();
}

const AtomicString& RenderStyle::hyphenString() const
{
    ASSERT(hyphens() != HyphensNone);

    const AtomicString& hyphenationString = rareInheritedData.get()->hyphenationString;
    if (!hyphenationString.isNull())
        return hyphenationString;

    // FIXME: This should depend on locale.
    static NeverDestroyed<AtomicString> hyphenMinusString(&hyphenMinus, 1);
    static NeverDestroyed<AtomicString> hyphenString(&hyphen, 1);
    return fontCascade().primaryFont().glyphForCharacter(hyphen) ? hyphenString : hyphenMinusString;
}

const AtomicString& RenderStyle::textEmphasisMarkString() const
{
    switch (textEmphasisMark()) {
    case TextEmphasisMarkNone:
        return nullAtom;
    case TextEmphasisMarkCustom:
        return textEmphasisCustomMark();
    case TextEmphasisMarkDot: {
        static NeverDestroyed<AtomicString> filledDotString(&bullet, 1);
        static NeverDestroyed<AtomicString> openDotString(&whiteBullet, 1);
        return textEmphasisFill() == TextEmphasisFillFilled ? filledDotString : openDotString;
    }
    case TextEmphasisMarkCircle: {
        static NeverDestroyed<AtomicString> filledCircleString(&blackCircle, 1);
        static NeverDestroyed<AtomicString> openCircleString(&whiteCircle, 1);
        return textEmphasisFill() == TextEmphasisFillFilled ? filledCircleString : openCircleString;
    }
    case TextEmphasisMarkDoubleCircle: {
        static NeverDestroyed<AtomicString> filledDoubleCircleString(&fisheye, 1);
        static NeverDestroyed<AtomicString> openDoubleCircleString(&bullseye, 1);
        return textEmphasisFill() == TextEmphasisFillFilled ? filledDoubleCircleString : openDoubleCircleString;
    }
    case TextEmphasisMarkTriangle: {
        static NeverDestroyed<AtomicString> filledTriangleString(&blackUpPointingTriangle, 1);
        static NeverDestroyed<AtomicString> openTriangleString(&whiteUpPointingTriangle, 1);
        return textEmphasisFill() == TextEmphasisFillFilled ? filledTriangleString : openTriangleString;
    }
    case TextEmphasisMarkSesame: {
        static NeverDestroyed<AtomicString> filledSesameString(&sesameDot, 1);
        static NeverDestroyed<AtomicString> openSesameString(&whiteSesameDot, 1);
        return textEmphasisFill() == TextEmphasisFillFilled ? filledSesameString : openSesameString;
    }
    case TextEmphasisMarkAuto:
        ASSERT_NOT_REACHED();
        return nullAtom;
    }

    ASSERT_NOT_REACHED();
    return nullAtom;
}

#if ENABLE(DASHBOARD_SUPPORT)
const Vector<StyleDashboardRegion>& RenderStyle::initialDashboardRegions()
{
    static NeverDestroyed<Vector<StyleDashboardRegion>> emptyList;
    return emptyList;
}

const Vector<StyleDashboardRegion>& RenderStyle::noneDashboardRegions()
{
    static NeverDestroyed<Vector<StyleDashboardRegion>> noneList;
    static bool noneListInitialized = false;

    if (!noneListInitialized) {
        StyleDashboardRegion region;
        region.label = emptyString();
        region.offset.top()  = Length();
        region.offset.right() = Length();
        region.offset.bottom() = Length();
        region.offset.left() = Length();
        region.type = StyleDashboardRegion::None;
        noneList.get().append(region);
        noneListInitialized = true;
    }
    return noneList;
}
#endif

void RenderStyle::adjustAnimations()
{
    AnimationList* animationList = rareNonInheritedData->m_animations.get();
    if (!animationList)
        return;

    // Get rid of empty animations and anything beyond them
    for (size_t i = 0; i < animationList->size(); ++i) {
        if (animationList->animation(i).isEmpty()) {
            animationList->resize(i);
            break;
        }
    }

    if (animationList->isEmpty()) {
        clearAnimations();
        return;
    }

    // Repeat patterns into layers that don't have some properties set.
    animationList->fillUnsetProperties();
}

void RenderStyle::adjustTransitions()
{
    AnimationList* transitionList = rareNonInheritedData->m_transitions.get();
    if (!transitionList)
        return;

    // Get rid of empty transitions and anything beyond them
    for (size_t i = 0; i < transitionList->size(); ++i) {
        if (transitionList->animation(i).isEmpty()) {
            transitionList->resize(i);
            break;
        }
    }

    if (transitionList->isEmpty()) {
        clearTransitions();
        return;
    }

    // Repeat patterns into layers that don't have some properties set.
    transitionList->fillUnsetProperties();

    // Make sure there are no duplicate properties. This is an O(n^2) algorithm
    // but the lists tend to be very short, so it is probably ok
    for (size_t i = 0; i < transitionList->size(); ++i) {
        for (size_t j = i+1; j < transitionList->size(); ++j) {
            if (transitionList->animation(i).property() == transitionList->animation(j).property()) {
                // toss i
                transitionList->remove(i);
                j = i;
            }
        }
    }
}

AnimationList& RenderStyle::ensureAnimations()
{
    if (!rareNonInheritedData.access()->m_animations)
        rareNonInheritedData.access()->m_animations = std::make_unique<AnimationList>();
    return *rareNonInheritedData->m_animations;
}

AnimationList& RenderStyle::ensureTransitions()
{
    if (!rareNonInheritedData.access()->m_transitions)
        rareNonInheritedData.access()->m_transitions = std::make_unique<AnimationList>();
    return *rareNonInheritedData->m_transitions;
}

const Animation* RenderStyle::transitionForProperty(CSSPropertyID property) const
{
    if (transitions()) {
        for (size_t i = 0; i < transitions()->size(); ++i) {
            const Animation& p = transitions()->animation(i);
            if (p.animationMode() == Animation::AnimateAll || p.property() == property) {
                return &p;
            }
        }
    }
    return 0;
}

const FontCascade& RenderStyle::fontCascade() const { return inherited->fontCascade; }
const FontMetrics& RenderStyle::fontMetrics() const { return inherited->fontCascade.fontMetrics(); }
const FontCascadeDescription& RenderStyle::fontDescription() const { return inherited->fontCascade.fontDescription(); }
float RenderStyle::specifiedFontSize() const { return fontDescription().specifiedSize(); }
float RenderStyle::computedFontSize() const { return fontDescription().computedSize(); }
int RenderStyle::fontSize() const { return inherited->fontCascade.pixelSize(); }

const Length& RenderStyle::wordSpacing() const { return rareInheritedData->wordSpacing; }
float RenderStyle::letterSpacing() const { return inherited->fontCascade.letterSpacing(); }

bool RenderStyle::setFontDescription(const FontCascadeDescription& v)
{
    if (inherited->fontCascade.fontDescription() != v) {
        inherited.access()->fontCascade = FontCascade(v, inherited->fontCascade.letterSpacing(), inherited->fontCascade.wordSpacing());
        return true;
    }
    return false;
}

#if ENABLE(TEXT_AUTOSIZING)
const Length& RenderStyle::specifiedLineHeight() const { return inherited->specifiedLineHeight; }
void RenderStyle::setSpecifiedLineHeight(Length v) { SET_VAR(inherited, specifiedLineHeight, v); }
#else
const Length& RenderStyle::specifiedLineHeight() const { return inherited->line_height; }
#endif

Length RenderStyle::lineHeight() const
{
    return inherited->line_height;
}
void RenderStyle::setLineHeight(Length specifiedLineHeight) { SET_VAR(inherited, line_height, specifiedLineHeight); }

int RenderStyle::computedLineHeight() const
{
    const Length& lh = lineHeight();

    // Negative value means the line height is not set. Use the font's built-in spacing.
    if (lh.isNegative())
        return fontMetrics().lineSpacing();

    if (lh.isPercentOrCalculated())
        return minimumValueForLength(lh, fontSize());

    return clampTo<int>(lh.value());
}

void RenderStyle::setWordSpacing(Length value)
{
    float fontWordSpacing;
    switch (value.type()) {
    case Auto:
        fontWordSpacing = 0;
        break;
    case Percent:
        fontWordSpacing = value.percent() * fontCascade().spaceWidth() / 100;
        break;
    case Fixed:
        fontWordSpacing = value.value();
        break;
    case Calculated:
        fontWordSpacing = value.nonNanCalculatedValue(maxValueForCssLength);
        break;
    default:
        ASSERT_NOT_REACHED();
        fontWordSpacing = 0;
        break;
    }
    inherited.access()->fontCascade.setWordSpacing(fontWordSpacing);
    rareInheritedData.access()->wordSpacing = WTFMove(value);
}

void RenderStyle::setLetterSpacing(float v) { inherited.access()->fontCascade.setLetterSpacing(v); }

void RenderStyle::setFontSize(float size)
{
    // size must be specifiedSize if Text Autosizing is enabled, but computedSize if text
    // zoom is enabled (if neither is enabled it's irrelevant as they're probably the same).

    ASSERT(std::isfinite(size));
    if (!std::isfinite(size) || size < 0)
        size = 0;
    else
        size = std::min(maximumAllowedFontSize, size);

    FontSelector* currentFontSelector = fontCascade().fontSelector();
    auto description = fontDescription();
    description.setSpecifiedSize(size);
    description.setComputedSize(size);

    setFontDescription(description);
    fontCascade().update(currentFontSelector);
}

#if ENABLE(VARIATION_FONTS)
void RenderStyle::setFontVariationSettings(FontVariationSettings settings)
{
    FontSelector* currentFontSelector = fontCascade().fontSelector();
    auto description = fontDescription();
    description.setVariationSettings(WTFMove(settings));

    setFontDescription(description);
    fontCascade().update(currentFontSelector);
}
#endif

void RenderStyle::getShadowExtent(const ShadowData* shadow, LayoutUnit &top, LayoutUnit &right, LayoutUnit &bottom, LayoutUnit &left) const
{
    top = 0;
    right = 0;
    bottom = 0;
    left = 0;

    for ( ; shadow; shadow = shadow->next()) {
        if (shadow->style() == Inset)
            continue;

        int extentAndSpread = shadow->paintingExtent() + shadow->spread();
        top = std::min<LayoutUnit>(top, shadow->y() - extentAndSpread);
        right = std::max<LayoutUnit>(right, shadow->x() + extentAndSpread);
        bottom = std::max<LayoutUnit>(bottom, shadow->y() + extentAndSpread);
        left = std::min<LayoutUnit>(left, shadow->x() - extentAndSpread);
    }
}

LayoutBoxExtent RenderStyle::getShadowInsetExtent(const ShadowData* shadow) const
{
    LayoutUnit top = 0;
    LayoutUnit right = 0;
    LayoutUnit bottom = 0;
    LayoutUnit left = 0;

    for ( ; shadow; shadow = shadow->next()) {
        if (shadow->style() == Normal)
            continue;

        int extentAndSpread = shadow->paintingExtent() + shadow->spread();
        top = std::max<LayoutUnit>(top, shadow->y() + extentAndSpread);
        right = std::min<LayoutUnit>(right, shadow->x() - extentAndSpread);
        bottom = std::min<LayoutUnit>(bottom, shadow->y() - extentAndSpread);
        left = std::max<LayoutUnit>(left, shadow->x() + extentAndSpread);
    }

    return LayoutBoxExtent(top, right, bottom, left);
}

void RenderStyle::getShadowHorizontalExtent(const ShadowData* shadow, LayoutUnit &left, LayoutUnit &right) const
{
    left = 0;
    right = 0;

    for ( ; shadow; shadow = shadow->next()) {
        if (shadow->style() == Inset)
            continue;

        int extentAndSpread = shadow->paintingExtent() + shadow->spread();
        left = std::min<LayoutUnit>(left, shadow->x() - extentAndSpread);
        right = std::max<LayoutUnit>(right, shadow->x() + extentAndSpread);
    }
}

void RenderStyle::getShadowVerticalExtent(const ShadowData* shadow, LayoutUnit &top, LayoutUnit &bottom) const
{
    top = 0;
    bottom = 0;

    for ( ; shadow; shadow = shadow->next()) {
        if (shadow->style() == Inset)
            continue;

        int extentAndSpread = shadow->paintingExtent() + shadow->spread();
        top = std::min<LayoutUnit>(top, shadow->y() - extentAndSpread);
        bottom = std::max<LayoutUnit>(bottom, shadow->y() + extentAndSpread);
    }
}

Color RenderStyle::colorIncludingFallback(int colorProperty, bool visitedLink) const
{
    Color result;
    EBorderStyle borderStyle = BNONE;
    switch (colorProperty) {
    case CSSPropertyBackgroundColor:
        return visitedLink ? visitedLinkBackgroundColor() : backgroundColor(); // Background color doesn't fall back.
    case CSSPropertyBorderLeftColor:
        result = visitedLink ? visitedLinkBorderLeftColor() : borderLeftColor();
        borderStyle = borderLeftStyle();
        break;
    case CSSPropertyBorderRightColor:
        result = visitedLink ? visitedLinkBorderRightColor() : borderRightColor();
        borderStyle = borderRightStyle();
        break;
    case CSSPropertyBorderTopColor:
        result = visitedLink ? visitedLinkBorderTopColor() : borderTopColor();
        borderStyle = borderTopStyle();
        break;
    case CSSPropertyBorderBottomColor:
        result = visitedLink ? visitedLinkBorderBottomColor() : borderBottomColor();
        borderStyle = borderBottomStyle();
        break;
    case CSSPropertyColor:
        result = visitedLink ? visitedLinkColor() : color();
        break;
    case CSSPropertyOutlineColor:
        result = visitedLink ? visitedLinkOutlineColor() : outlineColor();
        break;
    case CSSPropertyColumnRuleColor:
        result = visitedLink ? visitedLinkColumnRuleColor() : columnRuleColor();
        break;
    case CSSPropertyWebkitTextDecorationColor:
        // Text decoration color fallback is handled in RenderObject::decorationColor.
        return visitedLink ? visitedLinkTextDecorationColor() : textDecorationColor();
    case CSSPropertyWebkitTextEmphasisColor:
        result = visitedLink ? visitedLinkTextEmphasisColor() : textEmphasisColor();
        break;
    case CSSPropertyWebkitTextFillColor:
        result = visitedLink ? visitedLinkTextFillColor() : textFillColor();
        break;
    case CSSPropertyWebkitTextStrokeColor:
        result = visitedLink ? visitedLinkTextStrokeColor() : textStrokeColor();
        break;
    default:
        ASSERT_NOT_REACHED();
        break;
    }

    if (!result.isValid()) {
        if (!visitedLink && (borderStyle == INSET || borderStyle == OUTSET || borderStyle == RIDGE || borderStyle == GROOVE))
            result = Color(238, 238, 238);
        else
            result = visitedLink ? visitedLinkColor() : color();
    }
    return result;
}

Color RenderStyle::visitedDependentColor(int colorProperty) const
{
    Color unvisitedColor = colorIncludingFallback(colorProperty, false);
    if (insideLink() != InsideVisitedLink)
        return unvisitedColor;

    Color visitedColor = colorIncludingFallback(colorProperty, true);

    // Text decoration color validity is preserved (checked in RenderObject::decorationColor).
    if (colorProperty == CSSPropertyWebkitTextDecorationColor)
        return visitedColor;

    // FIXME: Technically someone could explicitly specify the color transparent, but for now we'll just
    // assume that if the background color is transparent that it wasn't set. Note that it's weird that
    // we're returning unvisited info for a visited link, but given our restriction that the alpha values
    // have to match, it makes more sense to return the unvisited background color if specified than it
    // does to return black. This behavior matches what Firefox 4 does as well.
    if (colorProperty == CSSPropertyBackgroundColor && visitedColor == Color::transparent)
        return unvisitedColor;

    // Take the alpha from the unvisited color, but get the RGB values from the visited color.
    return visitedColor.colorWithAlpha(unvisitedColor.alphaAsFloat());
}

const BorderValue& RenderStyle::borderBefore() const
{
    switch (writingMode()) {
    case TopToBottomWritingMode:
        return borderTop();
    case BottomToTopWritingMode:
        return borderBottom();
    case LeftToRightWritingMode:
        return borderLeft();
    case RightToLeftWritingMode:
        return borderRight();
    }
    ASSERT_NOT_REACHED();
    return borderTop();
}

const BorderValue& RenderStyle::borderAfter() const
{
    switch (writingMode()) {
    case TopToBottomWritingMode:
        return borderBottom();
    case BottomToTopWritingMode:
        return borderTop();
    case LeftToRightWritingMode:
        return borderRight();
    case RightToLeftWritingMode:
        return borderLeft();
    }
    ASSERT_NOT_REACHED();
    return borderBottom();
}

const BorderValue& RenderStyle::borderStart() const
{
    if (isHorizontalWritingMode())
        return isLeftToRightDirection() ? borderLeft() : borderRight();
    return isLeftToRightDirection() ? borderTop() : borderBottom();
}

const BorderValue& RenderStyle::borderEnd() const
{
    if (isHorizontalWritingMode())
        return isLeftToRightDirection() ? borderRight() : borderLeft();
    return isLeftToRightDirection() ? borderBottom() : borderTop();
}

float RenderStyle::borderBeforeWidth() const
{
    switch (writingMode()) {
    case TopToBottomWritingMode:
        return borderTopWidth();
    case BottomToTopWritingMode:
        return borderBottomWidth();
    case LeftToRightWritingMode:
        return borderLeftWidth();
    case RightToLeftWritingMode:
        return borderRightWidth();
    }
    ASSERT_NOT_REACHED();
    return borderTopWidth();
}

float RenderStyle::borderAfterWidth() const
{
    switch (writingMode()) {
    case TopToBottomWritingMode:
        return borderBottomWidth();
    case BottomToTopWritingMode:
        return borderTopWidth();
    case LeftToRightWritingMode:
        return borderRightWidth();
    case RightToLeftWritingMode:
        return borderLeftWidth();
    }
    ASSERT_NOT_REACHED();
    return borderBottomWidth();
}

float RenderStyle::borderStartWidth() const
{
    if (isHorizontalWritingMode())
        return isLeftToRightDirection() ? borderLeftWidth() : borderRightWidth();
    return isLeftToRightDirection() ? borderTopWidth() : borderBottomWidth();
}

float RenderStyle::borderEndWidth() const
{
    if (isHorizontalWritingMode())
        return isLeftToRightDirection() ? borderRightWidth() : borderLeftWidth();
    return isLeftToRightDirection() ? borderBottomWidth() : borderTopWidth();
}

void RenderStyle::setMarginStart(Length margin)
{
    if (isHorizontalWritingMode()) {
        if (isLeftToRightDirection())
            setMarginLeft(margin);
        else
            setMarginRight(margin);
    } else {
        if (isLeftToRightDirection())
            setMarginTop(margin);
        else
            setMarginBottom(margin);
    }
}

void RenderStyle::setMarginEnd(Length margin)
{
    if (isHorizontalWritingMode()) {
        if (isLeftToRightDirection())
            setMarginRight(margin);
        else
            setMarginLeft(margin);
    } else {
        if (isLeftToRightDirection())
            setMarginBottom(margin);
        else
            setMarginTop(margin);
    }
}

TextEmphasisMark RenderStyle::textEmphasisMark() const
{
    TextEmphasisMark mark = static_cast<TextEmphasisMark>(rareInheritedData->textEmphasisMark);
    if (mark != TextEmphasisMarkAuto)
        return mark;

    if (isHorizontalWritingMode())
        return TextEmphasisMarkDot;

    return TextEmphasisMarkSesame;
}

#if ENABLE(TOUCH_EVENTS)
Color RenderStyle::initialTapHighlightColor()
{
    return RenderTheme::tapHighlightColor();
}
#endif

LayoutBoxExtent RenderStyle::imageOutsets(const NinePieceImage& image) const
{
    return LayoutBoxExtent(NinePieceImage::computeOutset(image.outset().top(), borderTopWidth()),
                           NinePieceImage::computeOutset(image.outset().right(), borderRightWidth()),
                           NinePieceImage::computeOutset(image.outset().bottom(), borderBottomWidth()),
                           NinePieceImage::computeOutset(image.outset().left(), borderLeftWidth()));
}

std::pair<FontOrientation, NonCJKGlyphOrientation> RenderStyle::fontAndGlyphOrientation()
{
    // FIXME: TextOrientationSideways should map to sideways-left in vertical-lr, which is not supported yet.

    if (isHorizontalWritingMode())
        return { Horizontal, NonCJKGlyphOrientation::Mixed };

    switch (textOrientation()) {
    case TextOrientation::Mixed:
        return { Vertical, NonCJKGlyphOrientation::Mixed };
    case TextOrientation::Upright:
        return { Vertical, NonCJKGlyphOrientation::Upright };
    case TextOrientation::Sideways:
        return { Horizontal, NonCJKGlyphOrientation::Mixed };
    default:
        ASSERT_NOT_REACHED();
        return { Horizontal, NonCJKGlyphOrientation::Mixed };
    }
}

void RenderStyle::setBorderImageSource(RefPtr<StyleImage>&& image)
{
    if (surround->border.m_image.image() == image.get())
        return;
    surround.access()->border.m_image.setImage(WTFMove(image));
}

void RenderStyle::setBorderImageSlices(LengthBox slices)
{
    if (surround->border.m_image.imageSlices() == slices)
        return;
    surround.access()->border.m_image.setImageSlices(slices);
}

void RenderStyle::setBorderImageWidth(LengthBox slices)
{
    if (surround->border.m_image.borderSlices() == slices)
        return;
    surround.access()->border.m_image.setBorderSlices(slices);
}

void RenderStyle::setBorderImageOutset(LengthBox outset)
{
    if (surround->border.m_image.outset() == outset)
        return;
    surround.access()->border.m_image.setOutset(outset);
}

void RenderStyle::setColumnStylesFromPaginationMode(const Pagination::Mode& paginationMode)
{
    if (paginationMode == Pagination::Unpaginated)
        return;
    
    setColumnFill(ColumnFillAuto);
    
    switch (paginationMode) {
    case Pagination::LeftToRightPaginated:
        setColumnAxis(HorizontalColumnAxis);
        if (isHorizontalWritingMode())
            setColumnProgression(isLeftToRightDirection() ? NormalColumnProgression : ReverseColumnProgression);
        else
            setColumnProgression(isFlippedBlocksWritingMode() ? ReverseColumnProgression : NormalColumnProgression);
        break;
    case Pagination::RightToLeftPaginated:
        setColumnAxis(HorizontalColumnAxis);
        if (isHorizontalWritingMode())
            setColumnProgression(isLeftToRightDirection() ? ReverseColumnProgression : NormalColumnProgression);
        else
            setColumnProgression(isFlippedBlocksWritingMode() ? NormalColumnProgression : ReverseColumnProgression);
        break;
    case Pagination::TopToBottomPaginated:
        setColumnAxis(VerticalColumnAxis);
        if (isHorizontalWritingMode())
            setColumnProgression(isFlippedBlocksWritingMode() ? ReverseColumnProgression : NormalColumnProgression);
        else
            setColumnProgression(isLeftToRightDirection() ? NormalColumnProgression : ReverseColumnProgression);
        break;
    case Pagination::BottomToTopPaginated:
        setColumnAxis(VerticalColumnAxis);
        if (isHorizontalWritingMode())
            setColumnProgression(isFlippedBlocksWritingMode() ? NormalColumnProgression : ReverseColumnProgression);
        else
            setColumnProgression(isLeftToRightDirection() ? ReverseColumnProgression : NormalColumnProgression);
        break;
    case Pagination::Unpaginated:
        ASSERT_NOT_REACHED();
        break;
    }
}

#if ENABLE(CSS_SCROLL_SNAP)
ScrollSnapType RenderStyle::initialScrollSnapType()
{
    return { };
}

ScrollSnapAlign RenderStyle::initialScrollSnapAlign()
{
    return { };
}

const StyleScrollSnapArea& RenderStyle::scrollSnapArea() const
{
    return *rareNonInheritedData->m_scrollSnapArea;
}

const StyleScrollSnapPort& RenderStyle::scrollSnapPort() const
{
    return *rareNonInheritedData->m_scrollSnapPort;
}

const ScrollSnapType& RenderStyle::scrollSnapType() const
{
    return rareNonInheritedData->m_scrollSnapPort->type;
}

const LengthBox& RenderStyle::scrollPadding() const
{
    return rareNonInheritedData->m_scrollSnapPort->scrollPadding;
}

const Length& RenderStyle::scrollPaddingTop() const
{
    return scrollPadding().top();
}

const Length& RenderStyle::scrollPaddingBottom() const
{
    return scrollPadding().bottom();
}

const Length& RenderStyle::scrollPaddingLeft() const
{
    return scrollPadding().left();
}

const Length& RenderStyle::scrollPaddingRight() const
{
    return scrollPadding().right();
}

const ScrollSnapAlign& RenderStyle::scrollSnapAlign() const
{
    return rareNonInheritedData->m_scrollSnapArea->alignment;
}

const LengthBox& RenderStyle::scrollSnapMargin() const
{
    return rareNonInheritedData->m_scrollSnapArea->scrollSnapMargin;
}

const Length& RenderStyle::scrollSnapMarginTop() const
{
    return scrollSnapMargin().top();
}

const Length& RenderStyle::scrollSnapMarginBottom() const
{
    return scrollSnapMargin().bottom();
}

const Length& RenderStyle::scrollSnapMarginLeft() const
{
    return scrollSnapMargin().left();
}

const Length& RenderStyle::scrollSnapMarginRight() const
{
    return scrollSnapMargin().right();
}

void RenderStyle::setScrollSnapType(const ScrollSnapType& type)
{
    rareNonInheritedData.access()->m_scrollSnapPort.access()->type = type;
}

void RenderStyle::setScrollPaddingTop(const Length& length)
{
    rareNonInheritedData.access()->m_scrollSnapPort.access()->scrollPadding.setTop(length);
}

void RenderStyle::setScrollPaddingBottom(const Length& length)
{
    rareNonInheritedData.access()->m_scrollSnapPort.access()->scrollPadding.setBottom(length);
}

void RenderStyle::setScrollPaddingLeft(const Length& length)
{
    rareNonInheritedData.access()->m_scrollSnapPort.access()->scrollPadding.setLeft(length);
}

void RenderStyle::setScrollPaddingRight(const Length& length)
{
    rareNonInheritedData.access()->m_scrollSnapPort.access()->scrollPadding.setRight(length);
}

void RenderStyle::setScrollSnapAlign(const ScrollSnapAlign& alignment)
{
    rareNonInheritedData.access()->m_scrollSnapArea.access()->alignment = alignment;
}

void RenderStyle::setScrollSnapMarginTop(const Length& length)
{
    rareNonInheritedData.access()->m_scrollSnapArea.access()->scrollSnapMargin.setTop(length);
}

void RenderStyle::setScrollSnapMarginBottom(const Length& length)
{
    rareNonInheritedData.access()->m_scrollSnapArea.access()->scrollSnapMargin.setBottom(length);
}

void RenderStyle::setScrollSnapMarginLeft(const Length& length)
{
    rareNonInheritedData.access()->m_scrollSnapArea.access()->scrollSnapMargin.setLeft(length);
}

void RenderStyle::setScrollSnapMarginRight(const Length& length)
{
    rareNonInheritedData.access()->m_scrollSnapArea.access()->scrollSnapMargin.setRight(length);
}
#endif

bool RenderStyle::hasReferenceFilterOnly() const
{
    if (!hasFilter())
        return false;

    const FilterOperations& filterOperations = rareNonInheritedData->m_filter->m_operations;
    if (filterOperations.size() != 1)
        return false;

    const FilterOperation& filterOperation = *filterOperations.at(0);
    if (filterOperation.type() != FilterOperation::REFERENCE)
        return false;

    return true;
}

void RenderStyle::checkVariablesInCustomProperties()
{
    if (!rareInheritedData->m_customProperties->containsVariables())
        return;
    
    // Our first pass checks the variables for validity and replaces any properties that became
    // invalid with empty values.
    auto& customProperties = rareInheritedData.access()->m_customProperties.access()->values();
    HashSet<AtomicString> invalidProperties;
    for (auto entry : customProperties) {
        if (!entry.value->containsVariables())
            continue;
        HashSet<AtomicString> seenProperties;
        entry.value->checkVariablesForCycles(entry.key, customProperties, seenProperties, invalidProperties);
    }
    
    // Now insert invalid values.
    if (!invalidProperties.isEmpty()) {
        auto invalidValue = CSSCustomPropertyValue::createInvalid();
        for (auto& property : invalidProperties)
            customProperties.set(property, invalidValue.copyRef());
    }

    // Now that all of the properties have been tested for validity and replaced with
    // invalid values if they failed, we can perform variable substitution on the valid values.
    Vector<Ref<CSSCustomPropertyValue>> resolvedValues;
    for (auto entry : customProperties) {
        if (!entry.value->containsVariables())
            continue;
        entry.value->resolveVariableReferences(customProperties, resolvedValues);
    }
    
    // With all results computed, we can now mutate our table to eliminate the variables and
    // hold the final values. This way when we inherit, we don't end up resubstituting variables, etc.
    for (auto& resolvedValue : resolvedValues)
        customProperties.set(resolvedValue->name(), resolvedValue.copyRef());

    rareInheritedData.access()->m_customProperties.access()->setContainsVariables(false);
}

float RenderStyle::outlineWidth() const
{
    if (m_background->outline().style() == BNONE)
        return 0;
    if (outlineStyleIsAuto())
        return std::max(m_background->outline().width(), RenderTheme::platformFocusRingWidth());
    return m_background->outline().width();
}

float RenderStyle::outlineOffset() const
{
    if (m_background->outline().style() == BNONE)
        return 0;
    if (outlineStyleIsAuto())
        return (m_background->outline().offset() + RenderTheme::platformFocusRingOffset(outlineWidth()));
    return m_background->outline().offset();
}

bool RenderStyle::shouldPlaceBlockDirectionScrollbarOnLeft() const
{
    return !isLeftToRightDirection() && isHorizontalWritingMode();
}

} // namespace WebCore