/*
 * (C) 1999 Lars Knoll (knoll@kde.org)
 * (C) 2000 Dirk Mueller (mueller@kde.org)
 * Copyright (C) 2004-2007, 2013-2015 Apple Inc. All rights reserved.
 * Copyright (C) 2006 Andrew Wellington (proton@wiretapped.net)
 * Copyright (C) 2006 Graham Dennis (graham.dennis@gmail.com)
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 *
 */

#include "config.h"
#include "RenderText.h"

#include "AXObjectCache.h"
#include "BreakLines.h"
#include "BreakingContext.h"
#include "CharacterProperties.h"
#include "EllipsisBox.h"
#include "FloatQuad.h"
#include "Frame.h"
#include "FrameView.h"
#include "Hyphenation.h"
#include "InlineTextBox.h"
#include "Range.h"
#include "RenderBlock.h"
#include "RenderCombineText.h"
#include "RenderInline.h"
#include "RenderLayer.h"
#include "RenderView.h"
#include "Settings.h"
#include "SimpleLineLayoutFunctions.h"
#include "Text.h"
#include <wtf/text/TextBreakIterator.h>
#include "TextResourceDecoder.h"
#include "VisiblePosition.h"
#include <wtf/NeverDestroyed.h>
#include <wtf/text/StringBuffer.h>
#include <wtf/text/StringBuilder.h>
#include <wtf/unicode/CharacterNames.h>

#if PLATFORM(IOS)
#include "Document.h"
#include "EditorClient.h"
#include "LogicalSelectionOffsetCaches.h"
#include "Page.h"
#include "SelectionRect.h"
#endif

using namespace WTF;
using namespace Unicode;

namespace WebCore {

struct SameSizeAsRenderText : public RenderObject {
    uint32_t bitfields : 16;
#if ENABLE(TEXT_AUTOSIZING)
    float candidateTextSize;
#endif
    float widths[4];
    String text;
    void* pointers[2];
};

COMPILE_ASSERT(sizeof(RenderText) == sizeof(SameSizeAsRenderText), RenderText_should_stay_small);

class SecureTextTimer final : private TimerBase {
    WTF_MAKE_FAST_ALLOCATED;
public:
    explicit SecureTextTimer(RenderText&);
    void restart(unsigned offsetAfterLastTypedCharacter);

    unsigned takeOffsetAfterLastTypedCharacter();

private:
    void fired() override;
    RenderText& m_renderer;
    unsigned m_offsetAfterLastTypedCharacter { 0 };
};

typedef HashMap<RenderText*, std::unique_ptr<SecureTextTimer>> SecureTextTimerMap;

static SecureTextTimerMap& secureTextTimers()
{
    static NeverDestroyed<SecureTextTimerMap> map;
    return map.get();
}

inline SecureTextTimer::SecureTextTimer(RenderText& renderer)
    : m_renderer(renderer)
{
}

inline void SecureTextTimer::restart(unsigned offsetAfterLastTypedCharacter)
{
    m_offsetAfterLastTypedCharacter = offsetAfterLastTypedCharacter;
    startOneShot(m_renderer.settings().passwordEchoDurationInSeconds());
}

inline unsigned SecureTextTimer::takeOffsetAfterLastTypedCharacter()
{
    unsigned offset = m_offsetAfterLastTypedCharacter;
    m_offsetAfterLastTypedCharacter = 0;
    return offset;
}

void SecureTextTimer::fired()
{
    ASSERT(secureTextTimers().get(&m_renderer) == this);
    m_offsetAfterLastTypedCharacter = 0;
    m_renderer.setText(m_renderer.text(), true /* forcing setting text as it may be masked later */);
}

static HashMap<const RenderText*, String>& originalTextMap()
{
    static NeverDestroyed<HashMap<const RenderText*, String>> map;
    return map;
}

void makeCapitalized(String* string, UChar previous)
{
    // FIXME: Need to change this to use u_strToTitle instead of u_totitle and to consider locale.

    if (string->isNull())
        return;

    unsigned length = string->length();
    const StringImpl& stringImpl = *string->impl();

    if (length >= std::numeric_limits<unsigned>::max())
        CRASH();

    StringBuffer<UChar> stringWithPrevious(length + 1);
    stringWithPrevious[0] = previous == noBreakSpace ? ' ' : previous;
    for (unsigned i = 1; i < length + 1; i++) {
        // Replace &nbsp with a real space since ICU no longer treats &nbsp as a word separator.
        if (stringImpl[i - 1] == noBreakSpace)
            stringWithPrevious[i] = ' ';
        else
            stringWithPrevious[i] = stringImpl[i - 1];
    }

    UBreakIterator* boundary = wordBreakIterator(StringView(stringWithPrevious.characters(), length + 1));
    if (!boundary)
        return;

    StringBuilder result;
    result.reserveCapacity(length);

    int32_t endOfWord;
    int32_t startOfWord = ubrk_first(boundary);
    for (endOfWord = ubrk_next(boundary); endOfWord != UBRK_DONE; startOfWord = endOfWord, endOfWord = ubrk_next(boundary)) {
        if (startOfWord) // Ignore first char of previous string
            result.append(stringImpl[startOfWord - 1] == noBreakSpace ? noBreakSpace : u_totitle(stringWithPrevious[startOfWord]));
        for (int i = startOfWord + 1; i < endOfWord; i++)
            result.append(stringImpl[i - 1]);
    }

    *string = result.toString();
}

inline RenderText::RenderText(Node& node, const String& text)
    : RenderObject(node)
    , m_hasTab(false)
    , m_linesDirty(false)
    , m_containsReversedText(false)
    , m_isAllASCII(text.containsOnlyASCII())
    , m_knownToHaveNoOverflowAndNoFallbackFonts(false)
    , m_useBackslashAsYenSymbol(false)
    , m_originalTextDiffersFromRendered(false)
#if ENABLE(TEXT_AUTOSIZING)
    , m_candidateComputedTextSize(0)
#endif
    , m_minWidth(-1)
    , m_maxWidth(-1)
    , m_beginMinWidth(0)
    , m_endMinWidth(0)
    , m_text(text)
{
    ASSERT(!m_text.isNull());
    setIsText();
    m_canUseSimpleFontCodePath = computeCanUseSimpleFontCodePath();
    view().frameView().incrementVisuallyNonEmptyCharacterCount(textLength());
}

RenderText::RenderText(Text& textNode, const String& text)
    : RenderText(static_cast<Node&>(textNode), text)
{
}

RenderText::RenderText(Document& document, const String& text)
    : RenderText(static_cast<Node&>(document), text)
{
}

RenderText::~RenderText()
{
    // Do not add any code here. Add it to willBeDestroyed() instead.
    ASSERT(!originalTextMap().contains(this));
}

const char* RenderText::renderName() const
{
    return "RenderText";
}

Text* RenderText::textNode() const
{
    return downcast<Text>(RenderObject::node());
}

bool RenderText::isTextFragment() const
{
    return false;
}

bool RenderText::computeUseBackslashAsYenSymbol() const
{
    const RenderStyle& style = this->style();
    const auto& fontDescription = style.fontDescription();
    if (style.fontCascade().useBackslashAsYenSymbol())
        return true;
    if (fontDescription.isSpecifiedFont())
        return false;
    const TextEncoding* encoding = document().decoder() ? &document().decoder()->encoding() : 0;
    if (encoding && encoding->backslashAsCurrencySymbol() != '\\')
        return true;
    return false;
}

void RenderText::styleDidChange(StyleDifference diff, const RenderStyle* oldStyle)
{
    // There is no need to ever schedule repaints from a style change of a text run, since
    // we already did this for the parent of the text run.
    // We do have to schedule layouts, though, since a style change can force us to
    // need to relayout.
    if (diff == StyleDifferenceLayout) {
        setNeedsLayoutAndPrefWidthsRecalc();
        m_knownToHaveNoOverflowAndNoFallbackFonts = false;
    }

    const RenderStyle& newStyle = style();
    bool needsResetText = false;
    if (!oldStyle) {
        m_useBackslashAsYenSymbol = computeUseBackslashAsYenSymbol();
        needsResetText = m_useBackslashAsYenSymbol;
        // It should really be computed in the c'tor, but during construction we don't have parent yet -and RenderText style == parent()->style()
        m_canUseSimplifiedTextMeasuring = computeCanUseSimplifiedTextMeasuring();
    } else if (oldStyle->fontCascade().useBackslashAsYenSymbol() != newStyle.fontCascade().useBackslashAsYenSymbol()) {
        m_useBackslashAsYenSymbol = computeUseBackslashAsYenSymbol();
        needsResetText = true;
    }

    ETextTransform oldTransform = oldStyle ? oldStyle->textTransform() : TTNONE;
    ETextSecurity oldSecurity = oldStyle ? oldStyle->textSecurity() : TSNONE;
    if (needsResetText || oldTransform != newStyle.textTransform() || oldSecurity != newStyle.textSecurity())
        RenderText::setText(originalText(), true);
}

void RenderText::removeAndDestroyTextBoxes()
{
    if (!renderTreeBeingDestroyed())
        m_lineBoxes.removeAllFromParent(*this);
#if !ASSERT_WITH_SECURITY_IMPLICATION_DISABLED
    else
        m_lineBoxes.invalidateParentChildLists();
#endif
    m_lineBoxes.deleteAll();
}

void RenderText::willBeDestroyed()
{
    secureTextTimers().remove(this);

    removeAndDestroyTextBoxes();

    if (m_originalTextDiffersFromRendered)
        originalTextMap().remove(this);

    RenderObject::willBeDestroyed();
}

void RenderText::deleteLineBoxesBeforeSimpleLineLayout()
{
    m_lineBoxes.deleteAll();
}

String RenderText::originalText() const
{
    return m_originalTextDiffersFromRendered ? originalTextMap().get(this) : m_text;
}

void RenderText::absoluteRects(Vector<IntRect>& rects, const LayoutPoint& accumulatedOffset) const
{
    if (auto* layout = simpleLineLayout()) {
        rects.appendVector(SimpleLineLayout::collectAbsoluteRects(*this, *layout, accumulatedOffset));
        return;
    }
    rects.appendVector(m_lineBoxes.absoluteRects(accumulatedOffset));
}

Vector<IntRect> RenderText::absoluteRectsForRange(unsigned start, unsigned end, bool useSelectionHeight, bool* wasFixed) const
{
    const_cast<RenderText&>(*this).ensureLineBoxes();

    // Work around signed/unsigned issues. This function takes unsigneds, and is often passed UINT_MAX
    // to mean "all the way to the end". InlineTextBox coordinates are unsigneds, so changing this 
    // function to take ints causes various internal mismatches. But selectionRect takes ints, and 
    // passing UINT_MAX to it causes trouble. Ideally we'd change selectionRect to take unsigneds, but 
    // that would cause many ripple effects, so for now we'll just clamp our unsigned parameters to INT_MAX.
    ASSERT(end == UINT_MAX || end <= INT_MAX);
    ASSERT(start <= INT_MAX);
    start = std::min(start, static_cast<unsigned>(INT_MAX));
    end = std::min(end, static_cast<unsigned>(INT_MAX));
    
    return m_lineBoxes.absoluteRectsForRange(*this, start, end, useSelectionHeight, wasFixed);
}

#if PLATFORM(IOS)
// This function is similar in spirit to addLineBoxRects, but returns rectangles
// which are annotated with additional state which helps the iPhone draw selections in its unique way.
// Full annotations are added in this class.
void RenderText::collectSelectionRects(Vector<SelectionRect>& rects, unsigned start, unsigned end)
{
    // FIXME: Work around signed/unsigned issues. This function takes unsigneds, and is often passed UINT_MAX
    // to mean "all the way to the end". InlineTextBox coordinates are unsigneds, so changing this 
    // function to take ints causes various internal mismatches. But selectionRect takes ints, and 
    // passing UINT_MAX to it causes trouble. Ideally we'd change selectionRect to take unsigneds, but 
    // that would cause many ripple effects, so for now we'll just clamp our unsigned parameters to INT_MAX.
    ASSERT(end == std::numeric_limits<unsigned>::max() || end <= std::numeric_limits<int>::max());
    ASSERT(start <= std::numeric_limits<int>::max());
    start = std::min(start, static_cast<unsigned>(std::numeric_limits<int>::max()));
    end = std::min(end, static_cast<unsigned>(std::numeric_limits<int>::max()));

    for (InlineTextBox* box = firstTextBox(); box; box = box->nextTextBox()) {
        LayoutRect rect;
        // Note, box->end() returns the index of the last character, not the index past it.
        if (start <= box->start() && box->end() < end)
            rect = box->localSelectionRect(start, end);
        else {
            unsigned realEnd = std::min(box->end() + 1, end);
            rect = box->localSelectionRect(start, realEnd);
            if (rect.isEmpty())
                continue;
        }

        if (box->root().isFirstAfterPageBreak()) {
            if (box->isHorizontal())
                rect.shiftYEdgeTo(box->root().lineTopWithLeading());
            else
                rect.shiftXEdgeTo(box->root().lineTopWithLeading());
        }

        RenderBlock* containingBlock = this->containingBlock();
        // Map rect, extended left to leftOffset, and right to rightOffset, through transforms to get minX and maxX.
        LogicalSelectionOffsetCaches cache(*containingBlock);
        LayoutUnit leftOffset = containingBlock->logicalLeftSelectionOffset(*containingBlock, box->logicalTop(), cache);
        LayoutUnit rightOffset = containingBlock->logicalRightSelectionOffset(*containingBlock, box->logicalTop(), cache);
        LayoutRect extentsRect = rect;
        if (box->isHorizontal()) {
            extentsRect.setX(leftOffset);
            extentsRect.setWidth(rightOffset - leftOffset);
        } else {
            extentsRect.setY(leftOffset);
            extentsRect.setHeight(rightOffset - leftOffset);
        }
        extentsRect = localToAbsoluteQuad(FloatRect(extentsRect)).enclosingBoundingBox();
        if (!box->isHorizontal())
            extentsRect = extentsRect.transposedRect();
        bool isFirstOnLine = !box->previousOnLineExists();
        bool isLastOnLine = !box->nextOnLineExists();
        if (containingBlock->isRubyBase() || containingBlock->isRubyText())
            isLastOnLine = !containingBlock->containingBlock()->inlineBoxWrapper()->nextOnLineExists();

        bool containsStart = box->start() <= start && box->end() + 1 >= start;
        bool containsEnd = box->start() <= end && box->end() + 1 >= end;

        bool isFixed = false;
        IntRect absRect = localToAbsoluteQuad(FloatRect(rect), UseTransforms, &isFixed).enclosingBoundingBox();
        bool boxIsHorizontal = !box->isSVGInlineTextBox() ? box->isHorizontal() : !style().isVerticalWritingMode();
        // If the containing block is an inline element, we want to check the inlineBoxWrapper orientation
        // to determine the orientation of the block. In this case we also use the inlineBoxWrapper to
        // determine if the element is the last on the line.
        if (containingBlock->inlineBoxWrapper()) {
            if (containingBlock->inlineBoxWrapper()->isHorizontal() != boxIsHorizontal) {
                boxIsHorizontal = containingBlock->inlineBoxWrapper()->isHorizontal();
                isLastOnLine = !containingBlock->inlineBoxWrapper()->nextOnLineExists();
            }
        }

        rects.append(SelectionRect(absRect, box->direction(), extentsRect.x(), extentsRect.maxX(), extentsRect.maxY(), 0, box->isLineBreak(), isFirstOnLine, isLastOnLine, containsStart, containsEnd, boxIsHorizontal, isFixed, containingBlock->isRubyText(), view().pageNumberForBlockProgressionOffset(absRect.x())));
    }
}
#endif

Vector<FloatQuad> RenderText::absoluteQuadsClippedToEllipsis() const
{
    if (auto* layout = simpleLineLayout()) {
        ASSERT(style().textOverflow() != TextOverflowEllipsis);
        return SimpleLineLayout::collectAbsoluteQuads(*this, *layout, nullptr);
    }
    return m_lineBoxes.absoluteQuads(*this, nullptr, RenderTextLineBoxes::ClipToEllipsis);
}

void RenderText::absoluteQuads(Vector<FloatQuad>& quads, bool* wasFixed) const
{
    if (auto* layout = simpleLineLayout()) {
        quads.appendVector(SimpleLineLayout::collectAbsoluteQuads(*this, *layout, wasFixed));
        return;
    }
    quads.appendVector(m_lineBoxes.absoluteQuads(*this, wasFixed, RenderTextLineBoxes::NoClipping));
}

Vector<FloatQuad> RenderText::absoluteQuadsForRange(unsigned start, unsigned end, bool useSelectionHeight, bool* wasFixed) const
{
    // Work around signed/unsigned issues. This function takes unsigneds, and is often passed UINT_MAX
    // to mean "all the way to the end". InlineTextBox coordinates are unsigneds, so changing this
    // function to take ints causes various internal mismatches. But selectionRect takes ints, and
    // passing UINT_MAX to it causes trouble. Ideally we'd change selectionRect to take unsigneds, but
    // that would cause many ripple effects, so for now we'll just clamp our unsigned parameters to INT_MAX.
    ASSERT(end == UINT_MAX || end <= INT_MAX);
    ASSERT(start <= INT_MAX);
    start = std::min(start, static_cast<unsigned>(INT_MAX));
    end = std::min(end, static_cast<unsigned>(INT_MAX));
    if (simpleLineLayout() && !useSelectionHeight)
        return collectAbsoluteQuadsForRange(*this, start, end, *simpleLineLayout(), wasFixed);
    const_cast<RenderText&>(*this).ensureLineBoxes();
    return m_lineBoxes.absoluteQuadsForRange(*this, start, end, useSelectionHeight, wasFixed);
}

Position RenderText::positionForPoint(const LayoutPoint& point)
{
    if (simpleLineLayout() && parent()->firstChild() == parent()->lastChild()) {
        auto position = Position(textNode(), SimpleLineLayout::textOffsetForPoint(point, *this, *simpleLineLayout()));
        ASSERT(position == positionForPoint(point, nullptr).deepEquivalent());
        return position;
    }
    return positionForPoint(point, nullptr).deepEquivalent();
}

VisiblePosition RenderText::positionForPoint(const LayoutPoint& point, const RenderRegion*)
{
    ensureLineBoxes();
    return m_lineBoxes.positionForPoint(*this, point);
}

LayoutRect RenderText::localCaretRect(InlineBox* inlineBox, unsigned caretOffset, LayoutUnit* extraWidthToEndOfLine)
{
    if (!inlineBox)
        return LayoutRect();

    auto& box = downcast<InlineTextBox>(*inlineBox);
    float left = box.positionForOffset(caretOffset);
    return box.root().computeCaretRect(left, caretWidth, extraWidthToEndOfLine);
}

ALWAYS_INLINE float RenderText::widthFromCache(const FontCascade& f, unsigned start, unsigned len, float xPos, HashSet<const Font*>* fallbackFonts, GlyphOverflow* glyphOverflow, const RenderStyle& style) const
{
    if (style.hasTextCombine() && is<RenderCombineText>(*this)) {
        const RenderCombineText& combineText = downcast<RenderCombineText>(*this);
        if (combineText.isCombined())
            return combineText.combinedTextWidth(f);
    }

    if (f.isFixedPitch() && f.fontDescription().variantSettings().isAllNormal() && m_isAllASCII && (!glyphOverflow || !glyphOverflow->computeBounds)) {
        float monospaceCharacterWidth = f.spaceWidth();
        float w = 0;
        bool isSpace;
        ASSERT(m_text);
        StringImpl& text = *m_text.impl();
        for (unsigned i = start; i < start + len; i++) {
            char c = text[i];
            if (c <= ' ') {
                if (c == ' ' || c == '\n') {
                    w += monospaceCharacterWidth;
                    isSpace = true;
                } else if (c == '\t') {
                    if (style.collapseWhiteSpace()) {
                        w += monospaceCharacterWidth;
                        isSpace = true;
                    } else {
                        w += f.tabWidth(style.tabSize(), xPos + w);
                        isSpace = false;
                    }
                } else
                    isSpace = false;
            } else {
                w += monospaceCharacterWidth;
                isSpace = false;
            }
            if (isSpace && i > start)
                w += f.wordSpacing();
        }
        return w;
    }

    TextRun run = RenderBlock::constructTextRun(*this, start, len, style);
    run.setCharactersLength(textLength() - start);
    ASSERT(run.charactersLength() >= run.length());

    run.setCharacterScanForCodePath(!canUseSimpleFontCodePath());
    run.setTabSize(!style.collapseWhiteSpace(), style.tabSize());
    run.setXPos(xPos);
    return f.width(run, fallbackFonts, glyphOverflow);
}

inline bool isHangablePunctuationAtLineStart(UChar c)
{
    return U_GET_GC_MASK(c) & (U_GC_PS_MASK | U_GC_PI_MASK | U_GC_PF_MASK);
}

inline bool isHangablePunctuationAtLineEnd(UChar c)
{
    return U_GET_GC_MASK(c) & (U_GC_PE_MASK | U_GC_PI_MASK | U_GC_PF_MASK);
}

float RenderText::hangablePunctuationStartWidth(unsigned index) const
{
    unsigned len = textLength();
    if (!len || index >= len)
        return 0;

    ASSERT(m_text);
    StringImpl& text = *m_text.impl();
    
    if (!isHangablePunctuationAtLineStart(text[index]))
        return 0;

    const RenderStyle& style = this->style();
    const FontCascade& font = style.fontCascade();
        
    return widthFromCache(font, index, 1, 0, 0, 0, style);
}

float RenderText::hangablePunctuationEndWidth(unsigned index) const
{
    unsigned len = textLength();
    if (!len || index >= len)
        return 0;
    
    ASSERT(m_text);
    StringImpl& text = *m_text.impl();

    if (!isHangablePunctuationAtLineEnd(text[index]))
        return 0;
    
    const RenderStyle& style = this->style();
    const FontCascade& font = style.fontCascade();
    
    return widthFromCache(font, index, 1, 0, 0, 0, style);
}

bool RenderText::isHangableStopOrComma(UChar c) const
{
    return c == 0x002C || c == 0x002E || c == 0x060C || c == 0x06D4 || c == 0x3001
        || c == 0x3002 || c == 0xFF0C || c == 0xFF0E || c == 0xFE50 || c == 0xFE51
        || c == 0xFE52 || c == 0xFF61 || c == 0xFF64;
}

unsigned RenderText::firstCharacterIndexStrippingSpaces() const
{
    if (!style().collapseWhiteSpace())
        return 0;
    
    ASSERT(m_text);
    StringImpl& text = *m_text.impl();
    
    unsigned i = 0;
    for ( ; i < textLength(); ++i) {
        if (text[i] != ' ' && (text[i] != '\n' || style().preserveNewline()) && text[i] != '\t')
            break;
    }
    return i;
}

unsigned RenderText::lastCharacterIndexStrippingSpaces() const
{
    if (!textLength())
        return 0;

    if (!style().collapseWhiteSpace())
        return textLength() - 1;
    
    ASSERT(m_text);
    StringImpl& text = *m_text.impl();
    
    int i = textLength() - 1;
    for ( ; i  >= 0; --i) {
        if (text[i] != ' ' && (text[i] != '\n' || style().preserveNewline()) && text[i] != '\t')
            break;
    }
    return i;
}

void RenderText::trimmedPrefWidths(float leadWidth,
                                   float& beginMinW, bool& beginWS,
                                   float& endMinW, bool& endWS,
                                   bool& hasBreakableChar, bool& hasBreak,
                                   float& beginMaxW, float& endMaxW,
                                   float& minW, float& maxW, bool& stripFrontSpaces)
{
    const RenderStyle& style = this->style();
    bool collapseWhiteSpace = style.collapseWhiteSpace();
    if (!collapseWhiteSpace)
        stripFrontSpaces = false;

    if (m_hasTab || preferredLogicalWidthsDirty())
        computePreferredLogicalWidths(leadWidth);

    beginWS = !stripFrontSpaces && m_hasBeginWS;
    endWS = m_hasEndWS;

    unsigned len = textLength();

    if (!len || (stripFrontSpaces && text()->containsOnlyWhitespace())) {
        beginMinW = 0;
        endMinW = 0;
        beginMaxW = 0;
        endMaxW = 0;
        minW = 0;
        maxW = 0;
        hasBreak = false;
        return;
    }

    minW = m_minWidth;
    maxW = m_maxWidth;

    beginMinW = m_beginMinWidth;
    endMinW = m_endMinWidth;

    hasBreakableChar = m_hasBreakableChar;
    hasBreak = m_hasBreak;

    ASSERT(m_text);
    StringImpl& text = *m_text.impl();
    if (text[0] == space || (text[0] == newlineCharacter && !style.preserveNewline()) || text[0] == '\t') {
        const FontCascade& font = style.fontCascade(); // FIXME: This ignores first-line.
        if (stripFrontSpaces) {
            float spaceWidth = font.width(RenderBlock::constructTextRun(&space, 1, style));
            maxW -= spaceWidth;
        } else
            maxW += font.wordSpacing();
    }

    stripFrontSpaces = collapseWhiteSpace && m_hasEndWS;

    if (!style.autoWrap() || minW > maxW)
        minW = maxW;

    // Compute our max widths by scanning the string for newlines.
    if (hasBreak) {
        const FontCascade& f = style.fontCascade(); // FIXME: This ignores first-line.
        bool firstLine = true;
        beginMaxW = maxW;
        endMaxW = maxW;
        for (unsigned i = 0; i < len; i++) {
            unsigned linelen = 0;
            while (i + linelen < len && text[i + linelen] != '\n')
                linelen++;

            if (linelen) {
                endMaxW = widthFromCache(f, i, linelen, leadWidth + endMaxW, 0, 0, style);
                if (firstLine) {
                    firstLine = false;
                    leadWidth = 0;
                    beginMaxW = endMaxW;
                }
                i += linelen;
            } else if (firstLine) {
                beginMaxW = 0;
                firstLine = false;
                leadWidth = 0;
            }

            if (i == len - 1)
                // A <pre> run that ends with a newline, as in, e.g.,
                // <pre>Some text\n\n<span>More text</pre>
                endMaxW = 0;
        }
    }
}

static inline bool isSpaceAccordingToStyle(UChar c, const RenderStyle& style)
{
    return c == ' ' || (c == noBreakSpace && style.nbspMode() == SPACE);
}

float RenderText::minLogicalWidth() const
{
    if (preferredLogicalWidthsDirty())
        const_cast<RenderText*>(this)->computePreferredLogicalWidths(0);
        
    return m_minWidth;
}

float RenderText::maxLogicalWidth() const
{
    if (preferredLogicalWidthsDirty())
        const_cast<RenderText*>(this)->computePreferredLogicalWidths(0);
        
    return m_maxWidth;
}

LineBreakIteratorMode mapLineBreakToIteratorMode(LineBreak lineBreak)
{
    switch (lineBreak) {
    case LineBreakAuto:
    case LineBreakAfterWhiteSpace:
        return LineBreakIteratorMode::Default;
    case LineBreakLoose:
        return LineBreakIteratorMode::Loose;
    case LineBreakNormal:
        return LineBreakIteratorMode::Normal;
    case LineBreakStrict:
        return LineBreakIteratorMode::Strict;
    }
    ASSERT_NOT_REACHED();
    return LineBreakIteratorMode::Default;
}

void RenderText::computePreferredLogicalWidths(float leadWidth)
{
    HashSet<const Font*> fallbackFonts;
    GlyphOverflow glyphOverflow;
    computePreferredLogicalWidths(leadWidth, fallbackFonts, glyphOverflow);
    if (fallbackFonts.isEmpty() && !glyphOverflow.left && !glyphOverflow.right && !glyphOverflow.top && !glyphOverflow.bottom)
        m_knownToHaveNoOverflowAndNoFallbackFonts = true;
}

static inline float hyphenWidth(RenderText& renderer, const FontCascade& font)
{
    const RenderStyle& style = renderer.style();
    auto textRun = RenderBlock::constructTextRun(style.hyphenString().string(), style);
    return font.width(textRun);
}

static float maxWordFragmentWidth(RenderText& renderer, const RenderStyle& style, const FontCascade& font, StringView word, unsigned minimumPrefixLength, unsigned minimumSuffixLength, unsigned& suffixStart, HashSet<const Font*>& fallbackFonts, GlyphOverflow& glyphOverflow)
{
    suffixStart = 0;
    if (word.length() <= minimumSuffixLength)
        return 0;

    Vector<int, 8> hyphenLocations;
    ASSERT(word.length() >= minimumSuffixLength);
    unsigned hyphenLocation = word.length() - minimumSuffixLength;
    while ((hyphenLocation = lastHyphenLocation(word, hyphenLocation, style.locale())) >= std::max(minimumPrefixLength, 1U))
        hyphenLocations.append(hyphenLocation);

    if (hyphenLocations.isEmpty())
        return 0;

    hyphenLocations.reverse();

    // FIXME: Breaking the string at these places in the middle of words is completely broken with complex text.
    float minimumFragmentWidthToConsider = font.pixelSize() * 5 / 4 + hyphenWidth(renderer, font);
    float maxFragmentWidth = 0;
    for (size_t k = 0; k < hyphenLocations.size(); ++k) {
        int fragmentLength = hyphenLocations[k] - suffixStart;
        StringBuilder fragmentWithHyphen;
        fragmentWithHyphen.append(word.substring(suffixStart, fragmentLength));
        fragmentWithHyphen.append(style.hyphenString());

        TextRun run = RenderBlock::constructTextRun(fragmentWithHyphen.toString(), style);
        run.setCharactersLength(fragmentWithHyphen.length());
        run.setCharacterScanForCodePath(!renderer.canUseSimpleFontCodePath());
        float fragmentWidth = font.width(run, &fallbackFonts, &glyphOverflow);

        // Narrow prefixes are ignored. See tryHyphenating in RenderBlockLineLayout.cpp.
        if (fragmentWidth <= minimumFragmentWidthToConsider)
            continue;

        suffixStart += fragmentLength;
        maxFragmentWidth = std::max(maxFragmentWidth, fragmentWidth);
    }

    return maxFragmentWidth;
}

void RenderText::computePreferredLogicalWidths(float leadWidth, HashSet<const Font*>& fallbackFonts, GlyphOverflow& glyphOverflow)
{
    ASSERT(m_hasTab || preferredLogicalWidthsDirty() || !m_knownToHaveNoOverflowAndNoFallbackFonts);

    m_minWidth = 0;
    m_beginMinWidth = 0;
    m_endMinWidth = 0;
    m_maxWidth = 0;

    float currMaxWidth = 0;
    m_hasBreakableChar = false;
    m_hasBreak = false;
    m_hasTab = false;
    m_hasBeginWS = false;
    m_hasEndWS = false;

    const RenderStyle& style = this->style();
    const FontCascade& font = style.fontCascade(); // FIXME: This ignores first-line.
    float wordSpacing = font.wordSpacing();
    unsigned len = textLength();
    auto iteratorMode = mapLineBreakToIteratorMode(style.lineBreak());
    LazyLineBreakIterator breakIterator(m_text, style.locale(), iteratorMode);
    bool needsWordSpacing = false;
    bool ignoringSpaces = false;
    bool isSpace = false;
    bool firstWord = true;
    bool firstLine = true;
    std::optional<unsigned> nextBreakable;
    unsigned lastWordBoundary = 0;

    // Non-zero only when kerning is enabled, in which case we measure words with their trailing
    // space, then subtract its width.
    WordTrailingSpace wordTrailingSpace(style);
    // If automatic hyphenation is allowed, we keep track of the width of the widest word (or word
    // fragment) encountered so far, and only try hyphenating words that are wider.
    float maxWordWidth = std::numeric_limits<float>::max();
    unsigned minimumPrefixLength = 0;
    unsigned minimumSuffixLength = 0;
    if (style.hyphens() == HyphensAuto && canHyphenate(style.locale())) {
        maxWordWidth = 0;

        // Map 'hyphenate-limit-{before,after}: auto;' to 2.
        auto before = style.hyphenationLimitBefore();
        minimumPrefixLength = before < 0 ? 2 : before;

        auto after = style.hyphenationLimitAfter();
        minimumSuffixLength = after < 0 ? 2 : after;
    }

    std::optional<int> firstGlyphLeftOverflow;

    bool breakNBSP = style.autoWrap() && style.nbspMode() == SPACE;
    
    // Note the deliberate omission of word-wrap and overflow-wrap from this breakAll check. Those
    // do not affect minimum preferred sizes. Note that break-word is a non-standard value for
    // word-break, but we support it as though it means break-all.
    bool breakAll = (style.wordBreak() == BreakAllWordBreak || style.wordBreak() == BreakWordBreak) && style.autoWrap();
    bool keepAllWords = style.wordBreak() == KeepAllWordBreak;
    bool canUseLineBreakShortcut = iteratorMode == LineBreakIteratorMode::Default;

    for (unsigned i = 0; i < len; i++) {
        UChar c = uncheckedCharacterAt(i);

        bool previousCharacterIsSpace = isSpace;

        bool isNewline = false;
        if (c == '\n') {
            if (style.preserveNewline()) {
                m_hasBreak = true;
                isNewline = true;
                isSpace = false;
            } else
                isSpace = true;
        } else if (c == '\t') {
            if (!style.collapseWhiteSpace()) {
                m_hasTab = true;
                isSpace = false;
            } else
                isSpace = true;
        } else
            isSpace = c == ' ';

        if ((isSpace || isNewline) && !i)
            m_hasBeginWS = true;
        if ((isSpace || isNewline) && i == len - 1)
            m_hasEndWS = true;

        ignoringSpaces |= style.collapseWhiteSpace() && previousCharacterIsSpace && isSpace;
        ignoringSpaces &= isSpace;

        // Ignore spaces and soft hyphens
        if (ignoringSpaces) {
            ASSERT(lastWordBoundary == i);
            lastWordBoundary++;
            continue;
        } else if (c == softHyphen && style.hyphens() != HyphensNone) {
            ASSERT(i >= lastWordBoundary);
            currMaxWidth += widthFromCache(font, lastWordBoundary, i - lastWordBoundary, leadWidth + currMaxWidth, &fallbackFonts, &glyphOverflow, style);
            if (!firstGlyphLeftOverflow)
                firstGlyphLeftOverflow = glyphOverflow.left;
            lastWordBoundary = i + 1;
            continue;
        }

        bool hasBreak = breakAll || isBreakable(breakIterator, i, nextBreakable, breakNBSP, canUseLineBreakShortcut, keepAllWords);
        bool betweenWords = true;
        unsigned j = i;
        while (c != '\n' && !isSpaceAccordingToStyle(c, style) && c != '\t' && (c != softHyphen || style.hyphens() == HyphensNone)) {
            j++;
            if (j == len)
                break;
            c = uncheckedCharacterAt(j);
            if (isBreakable(breakIterator, j, nextBreakable, breakNBSP, canUseLineBreakShortcut, keepAllWords) && characterAt(j - 1) != softHyphen)
                break;
            if (breakAll) {
                betweenWords = false;
                break;
            }
        }

        unsigned wordLen = j - i;
        if (wordLen) {
            float currMinWidth = 0;
            bool isSpace = (j < len) && isSpaceAccordingToStyle(c, style);
            float w;
            std::optional<float> wordTrailingSpaceWidth;
            if (isSpace)
                wordTrailingSpaceWidth = wordTrailingSpace.width(fallbackFonts);
            if (wordTrailingSpaceWidth)
                w = widthFromCache(font, i, wordLen + 1, leadWidth + currMaxWidth, &fallbackFonts, &glyphOverflow, style) - wordTrailingSpaceWidth.value();
            else {
                w = widthFromCache(font, i, wordLen, leadWidth + currMaxWidth, &fallbackFonts, &glyphOverflow, style);
                if (c == softHyphen && style.hyphens() != HyphensNone)
                    currMinWidth = hyphenWidth(*this, font);
            }

            if (w > maxWordWidth) {
                unsigned suffixStart;
                float maxFragmentWidth = maxWordFragmentWidth(*this, style, font, StringView(m_text).substring(i, wordLen), minimumPrefixLength, minimumSuffixLength, suffixStart, fallbackFonts, glyphOverflow);

                if (suffixStart) {
                    float suffixWidth;
                    std::optional<float> wordTrailingSpaceWidth;
                    if (isSpace)
                        wordTrailingSpaceWidth = wordTrailingSpace.width(fallbackFonts);
                    if (wordTrailingSpaceWidth)
                        suffixWidth = widthFromCache(font, i + suffixStart, wordLen - suffixStart + 1, leadWidth + currMaxWidth, 0, 0, style) - wordTrailingSpaceWidth.value();
                    else
                        suffixWidth = widthFromCache(font, i + suffixStart, wordLen - suffixStart, leadWidth + currMaxWidth, 0, 0, style);

                    maxFragmentWidth = std::max(maxFragmentWidth, suffixWidth);

                    currMinWidth += maxFragmentWidth - w;
                    maxWordWidth = std::max(maxWordWidth, maxFragmentWidth);
                } else
                    maxWordWidth = w;
            }

            if (!firstGlyphLeftOverflow)
                firstGlyphLeftOverflow = glyphOverflow.left;
            currMinWidth += w;
            if (betweenWords) {
                if (lastWordBoundary == i)
                    currMaxWidth += w;
                else {
                    ASSERT(j >= lastWordBoundary);
                    currMaxWidth += widthFromCache(font, lastWordBoundary, j - lastWordBoundary, leadWidth + currMaxWidth, &fallbackFonts, &glyphOverflow, style);
                }
                lastWordBoundary = j;
            }

            bool isCollapsibleWhiteSpace = (j < len) && style.isCollapsibleWhiteSpace(c);
            if (j < len && style.autoWrap())
                m_hasBreakableChar = true;

            // Add in wordSpacing to our currMaxWidth, but not if this is the last word on a line or the
            // last word in the run.
            if ((isSpace || isCollapsibleWhiteSpace) && !containsOnlyWhitespace(j, len-j))
                currMaxWidth += wordSpacing;

            if (firstWord) {
                firstWord = false;
                // If the first character in the run is breakable, then we consider ourselves to have a beginning
                // minimum width of 0, since a break could occur right before our run starts, preventing us from ever
                // being appended to a previous text run when considering the total minimum width of the containing block.
                if (hasBreak)
                    m_hasBreakableChar = true;
                m_beginMinWidth = hasBreak ? 0 : currMinWidth;
            }
            m_endMinWidth = currMinWidth;

            m_minWidth = std::max(currMinWidth, m_minWidth);

            i += wordLen - 1;
        } else {
            // Nowrap can never be broken, so don't bother setting the
            // breakable character boolean. Pre can only be broken if we encounter a newline.
            if (style.autoWrap() || isNewline)
                m_hasBreakableChar = true;

            if (isNewline) { // Only set if preserveNewline was true and we saw a newline.
                if (firstLine) {
                    firstLine = false;
                    leadWidth = 0;
                    if (!style.autoWrap())
                        m_beginMinWidth = currMaxWidth;
                }

                if (currMaxWidth > m_maxWidth)
                    m_maxWidth = currMaxWidth;
                currMaxWidth = 0;
            } else {
                TextRun run = RenderBlock::constructTextRun(*this, i, 1, style);
                run.setCharactersLength(len - i);
                ASSERT(run.charactersLength() >= run.length());
                run.setTabSize(!style.collapseWhiteSpace(), style.tabSize());
                run.setXPos(leadWidth + currMaxWidth);

                currMaxWidth += font.width(run, &fallbackFonts);
                glyphOverflow.right = 0;
                needsWordSpacing = isSpace && !previousCharacterIsSpace && i == len - 1;
            }
            ASSERT(lastWordBoundary == i);
            lastWordBoundary++;
        }
    }

    glyphOverflow.left = firstGlyphLeftOverflow.value_or(glyphOverflow.left);

    if ((needsWordSpacing && len > 1) || (ignoringSpaces && !firstWord))
        currMaxWidth += wordSpacing;

    m_maxWidth = std::max(currMaxWidth, m_maxWidth);

    if (!style.autoWrap())
        m_minWidth = m_maxWidth;

    if (style.whiteSpace() == PRE) {
        if (firstLine)
            m_beginMinWidth = m_maxWidth;
        m_endMinWidth = currMaxWidth;
    }

    setPreferredLogicalWidthsDirty(false);
}

bool RenderText::isAllCollapsibleWhitespace() const
{
    const RenderStyle& style = this->style();
    unsigned length = textLength();
    if (is8Bit()) {
        for (unsigned i = 0; i < length; ++i) {
            if (!style.isCollapsibleWhiteSpace(characters8()[i]))
                return false;
        }
        return true;
    }
    for (unsigned i = 0; i < length; ++i) {
        if (!style.isCollapsibleWhiteSpace(characters16()[i]))
            return false;
    }
    return true;
}
    
bool RenderText::containsOnlyWhitespace(unsigned from, unsigned len) const
{
    ASSERT(m_text);
    StringImpl& text = *m_text.impl();
    unsigned currPos;
    for (currPos = from;
         currPos < from + len && (text[currPos] == '\n' || text[currPos] == ' ' || text[currPos] == '\t');
         currPos++) { }
    return currPos >= (from + len);
}

IntPoint RenderText::firstRunLocation() const
{
    if (auto* layout = simpleLineLayout())
        return SimpleLineLayout::computeFirstRunLocation(*this, *layout);

    return m_lineBoxes.firstRunLocation();
}

void RenderText::setSelectionState(SelectionState state)
{
    if (state != SelectionNone)
        ensureLineBoxes();

    RenderObject::setSelectionState(state);

    if (canUpdateSelectionOnRootLineBoxes())
        m_lineBoxes.setSelectionState(*this, state);

    // The containing block can be null in case of an orphaned tree.
    RenderBlock* containingBlock = this->containingBlock();
    if (containingBlock && !containingBlock->isRenderView())
        containingBlock->setSelectionState(state);
}

void RenderText::setTextWithOffset(const String& text, unsigned offset, unsigned len, bool force)
{
    if (!force && m_text == text)
        return;

    int delta = text.length() - textLength();
    unsigned end = len ? offset + len - 1 : offset;

    m_linesDirty = simpleLineLayout() || m_lineBoxes.dirtyRange(*this, offset, end, delta);

    setText(text, force || m_linesDirty);
}

static inline bool isInlineFlowOrEmptyText(const RenderObject& renderer)
{
    if (is<RenderInline>(renderer))
        return true;
    if (!is<RenderText>(renderer))
        return false;
    StringImpl* text = downcast<RenderText>(renderer).text();
    if (!text)
        return true;
    return !text->length();
}

UChar RenderText::previousCharacter() const
{
    // find previous text renderer if one exists
    const RenderObject* previousText = this;
    while ((previousText = previousText->previousInPreOrder()))
        if (!isInlineFlowOrEmptyText(*previousText))
            break;
    UChar prev = ' ';
    if (is<RenderText>(previousText)) {
        if (StringImpl* previousString = downcast<RenderText>(*previousText).text())
            prev = (*previousString)[previousString->length() - 1];
    }
    return prev;
}

LayoutUnit RenderText::topOfFirstText() const
{
    return firstTextBox()->root().lineTop();
}

void applyTextTransform(const RenderStyle& style, String& text, UChar previousCharacter)
{
    switch (style.textTransform()) {
    case TTNONE:
        break;
    case CAPITALIZE:
        makeCapitalized(&text, previousCharacter);
        break;
    case UPPERCASE:
        text = text.convertToUppercaseWithLocale(style.locale());
        break;
    case LOWERCASE:
        text = text.convertToLowercaseWithLocale(style.locale());
        break;
    }
}

void RenderText::setRenderedText(const String& text)
{
    ASSERT(!text.isNull());

    String originalText = this->originalText();

    m_text = text;

    if (m_useBackslashAsYenSymbol)
        m_text.replace('\\', yenSign);

    ASSERT(m_text);

    applyTextTransform(style(), m_text, previousCharacter());

    switch (style().textSecurity()) {
    case TSNONE:
        break;
#if !PLATFORM(IOS)
    // We use the same characters here as for list markers.
    // See the listMarkerText function in RenderListMarker.cpp.
    case TSCIRCLE:
        secureText(whiteBullet);
        break;
    case TSDISC:
        secureText(bullet);
        break;
    case TSSQUARE:
        secureText(blackSquare);
        break;
#else
    // FIXME: Why this quirk on iOS?
    case TSCIRCLE:
    case TSDISC:
    case TSSQUARE:
        secureText(blackCircle);
        break;
#endif
    }

    ASSERT(!m_text.isNull());

    m_isAllASCII = m_text.containsOnlyASCII();
    m_canUseSimpleFontCodePath = computeCanUseSimpleFontCodePath();
    m_canUseSimplifiedTextMeasuring = computeCanUseSimplifiedTextMeasuring();
    
    if (m_text != originalText) {
        originalTextMap().set(this, originalText);
        m_originalTextDiffersFromRendered = true;
    } else if (m_originalTextDiffersFromRendered) {
        originalTextMap().remove(this);
        m_originalTextDiffersFromRendered = false;
    }
}

void RenderText::secureText(UChar maskingCharacter)
{
    // This hides the text by replacing all the characters with the masking character.
    // Offsets within the hidden text have to match offsets within the original text
    // to handle things like carets and selection, so this won't work right if any
    // of the characters are surrogate pairs or combining marks. Thus, this function
    // does not attempt to handle either of those.

    unsigned length = textLength();
    if (!length)
        return;

    UChar characterToReveal = 0;
    unsigned revealedCharactersOffset = 0;

    if (SecureTextTimer* timer = secureTextTimers().get(this)) {
        // We take the offset out of the timer to make this one-shot. We count on this being called only once.
        // If it's called a second time we assume the text is different and a character should not be revealed.
        revealedCharactersOffset = timer->takeOffsetAfterLastTypedCharacter();
        if (revealedCharactersOffset && revealedCharactersOffset <= length)
            characterToReveal = m_text[--revealedCharactersOffset];
    }

    UChar* characters;
    m_text = String::createUninitialized(length, characters);

    for (unsigned i = 0; i < length; ++i)
        characters[i] = maskingCharacter;
    if (characterToReveal)
        characters[revealedCharactersOffset] = characterToReveal;
}

bool RenderText::computeCanUseSimplifiedTextMeasuring() const
{
    if (!m_canUseSimpleFontCodePath)
        return false;
    
    auto& font = style().fontCascade();
    if (font.wordSpacing() || font.letterSpacing())
        return false;

    // Additional check on the font codepath.
    TextRun run(m_text);
    run.setCharacterScanForCodePath(false);
    if (font.codePath(run) != FontCascade::Simple)
        return false;

    auto whitespaceIsCollapsed = style().collapseWhiteSpace();
    for (unsigned i = 0; i < m_text.length(); ++i) {
        if ((!whitespaceIsCollapsed && m_text[i] == '\t') || m_text[i] == noBreakSpace || m_text[i] >= HiraganaLetterSmallA)
            return false;
    }
    return true;
}

void RenderText::setText(const String& text, bool force)
{
    ASSERT(!text.isNull());

    if (!force && text == originalText())
        return;

    m_text = text;
    if (m_originalTextDiffersFromRendered) {
        originalTextMap().remove(this);
        m_originalTextDiffersFromRendered = false;
    }

    setRenderedText(text);

    setNeedsLayoutAndPrefWidthsRecalc();
    m_knownToHaveNoOverflowAndNoFallbackFonts = false;

    if (is<RenderBlockFlow>(*parent()))
        downcast<RenderBlockFlow>(*parent()).invalidateLineLayoutPath();
    
    if (AXObjectCache* cache = document().existingAXObjectCache())
        cache->textChanged(this);
}

String RenderText::textWithoutConvertingBackslashToYenSymbol() const
{
    if (!m_useBackslashAsYenSymbol || style().textSecurity() != TSNONE)
        return text();

    String text = originalText();
    applyTextTransform(style(), text, previousCharacter());
    return text;
}

void RenderText::dirtyLineBoxes(bool fullLayout)
{
    if (fullLayout)
        m_lineBoxes.deleteAll();
    else if (!m_linesDirty)
        m_lineBoxes.dirtyAll();
    m_linesDirty = false;
}

std::unique_ptr<InlineTextBox> RenderText::createTextBox()
{
    return std::make_unique<InlineTextBox>(*this);
}

void RenderText::positionLineBox(InlineTextBox& textBox)
{
    if (!textBox.len())
        return;
    m_containsReversedText |= !textBox.isLeftToRightDirection();
}

void RenderText::ensureLineBoxes()
{
    if (!is<RenderBlockFlow>(*parent()))
        return;
    downcast<RenderBlockFlow>(*parent()).ensureLineBoxes();
}

const SimpleLineLayout::Layout* RenderText::simpleLineLayout() const
{
    if (!is<RenderBlockFlow>(*parent()))
        return nullptr;
    return downcast<RenderBlockFlow>(*parent()).simpleLineLayout();
}

float RenderText::width(unsigned from, unsigned len, float xPos, bool firstLine, HashSet<const Font*>* fallbackFonts, GlyphOverflow* glyphOverflow) const
{
    if (from >= textLength())
        return 0;

    if (from + len > textLength())
        len = textLength() - from;

    const RenderStyle& lineStyle = firstLine ? firstLineStyle() : style();
    return width(from, len, lineStyle.fontCascade(), xPos, fallbackFonts, glyphOverflow);
}

float RenderText::width(unsigned from, unsigned len, const FontCascade& f, float xPos, HashSet<const Font*>* fallbackFonts, GlyphOverflow* glyphOverflow) const
{
    ASSERT(from + len <= textLength());
    if (!textLength())
        return 0;

    const RenderStyle& style = this->style();
    float w;
    if (&f == &style.fontCascade()) {
        if (!style.preserveNewline() && !from && len == textLength() && (!glyphOverflow || !glyphOverflow->computeBounds)) {
            if (fallbackFonts) {
                ASSERT(glyphOverflow);
                if (preferredLogicalWidthsDirty() || !m_knownToHaveNoOverflowAndNoFallbackFonts) {
                    const_cast<RenderText*>(this)->computePreferredLogicalWidths(0, *fallbackFonts, *glyphOverflow);
                    if (fallbackFonts->isEmpty() && !glyphOverflow->left && !glyphOverflow->right && !glyphOverflow->top && !glyphOverflow->bottom)
                        m_knownToHaveNoOverflowAndNoFallbackFonts = true;
                }
                w = m_maxWidth;
            } else
                w = maxLogicalWidth();
        } else
            w = widthFromCache(f, from, len, xPos, fallbackFonts, glyphOverflow, style);
    } else {
        TextRun run = RenderBlock::constructTextRun(*this, from, len, style);
        run.setCharactersLength(textLength() - from);
        ASSERT(run.charactersLength() >= run.length());

        run.setCharacterScanForCodePath(!canUseSimpleFontCodePath());
        run.setTabSize(!style.collapseWhiteSpace(), style.tabSize());
        run.setXPos(xPos);
        w = f.width(run, fallbackFonts, glyphOverflow);
    }

    return w;
}

IntRect RenderText::linesBoundingBox() const
{
    if (auto* layout = simpleLineLayout())
        return SimpleLineLayout::computeBoundingBox(*this, *layout);

    return m_lineBoxes.boundingBox(*this);
}

LayoutRect RenderText::linesVisualOverflowBoundingBox() const
{
    ASSERT(!simpleLineLayout());
    return m_lineBoxes.visualOverflowBoundingBox(*this);
}

LayoutRect RenderText::clippedOverflowRectForRepaint(const RenderLayerModelObject* repaintContainer) const
{
    RenderObject* rendererToRepaint = containingBlock();

    // Do not cross self-painting layer boundaries.
    RenderObject& enclosingLayerRenderer = enclosingLayer()->renderer();
    if (&enclosingLayerRenderer != rendererToRepaint && !rendererToRepaint->isDescendantOf(&enclosingLayerRenderer))
        rendererToRepaint = &enclosingLayerRenderer;

    // The renderer we chose to repaint may be an ancestor of repaintContainer, but we need to do a repaintContainer-relative repaint.
    if (repaintContainer && repaintContainer != rendererToRepaint && !rendererToRepaint->isDescendantOf(repaintContainer))
        return repaintContainer->clippedOverflowRectForRepaint(repaintContainer);

    return rendererToRepaint->clippedOverflowRectForRepaint(repaintContainer);
}

LayoutRect RenderText::collectSelectionRectsForLineBoxes(const RenderLayerModelObject* repaintContainer, bool clipToVisibleContent, Vector<LayoutRect>* rects)
{
    ASSERT(!needsLayout());
    ASSERT(!simpleLineLayout());

    if (selectionState() == SelectionNone)
        return LayoutRect();
    if (!containingBlock())
        return LayoutRect();

    // Now calculate startPos and endPos for painting selection.
    // We include a selection while endPos > 0
    unsigned startPos, endPos;
    if (selectionState() == SelectionInside) {
        // We are fully selected.
        startPos = 0;
        endPos = textLength();
    } else {
        selectionStartEnd(startPos, endPos);
        if (selectionState() == SelectionStart)
            endPos = textLength();
        else if (selectionState() == SelectionEnd)
            startPos = 0;
    }

    if (startPos == endPos)
        return IntRect();

    LayoutRect resultRect;
    if (!rects)
        resultRect = m_lineBoxes.selectionRectForRange(startPos, endPos);
    else {
        m_lineBoxes.collectSelectionRectsForRange(startPos, endPos, *rects);
        for (auto& rect : *rects) {
            resultRect.unite(rect);
            rect = localToContainerQuad(FloatRect(rect), repaintContainer).enclosingBoundingBox();
        }
    }

    if (clipToVisibleContent)
        return computeRectForRepaint(resultRect, repaintContainer);
    return localToContainerQuad(FloatRect(resultRect), repaintContainer).enclosingBoundingBox();
}

LayoutRect RenderText::collectSelectionRectsForLineBoxes(const RenderLayerModelObject* repaintContainer, bool clipToVisibleContent, Vector<LayoutRect>& rects)
{
    return collectSelectionRectsForLineBoxes(repaintContainer, clipToVisibleContent, &rects);
}

LayoutRect RenderText::selectionRectForRepaint(const RenderLayerModelObject* repaintContainer, bool clipToVisibleContent)
{
    return collectSelectionRectsForLineBoxes(repaintContainer, clipToVisibleContent, nullptr);
}

int RenderText::caretMinOffset() const
{
    if (auto* layout = simpleLineLayout())
        return SimpleLineLayout::findCaretMinimumOffset(*this, *layout);
    return m_lineBoxes.caretMinOffset();
}

int RenderText::caretMaxOffset() const
{
    if (auto* layout = simpleLineLayout())
        return SimpleLineLayout::findCaretMaximumOffset(*this, *layout);
    return m_lineBoxes.caretMaxOffset(*this);
}

unsigned RenderText::countRenderedCharacterOffsetsUntil(unsigned offset) const
{
    ASSERT(!simpleLineLayout());
    return m_lineBoxes.countCharacterOffsetsUntil(offset);
}

bool RenderText::containsRenderedCharacterOffset(unsigned offset) const
{
    ASSERT(!simpleLineLayout());
    return m_lineBoxes.containsOffset(*this, offset, RenderTextLineBoxes::CharacterOffset);
}

bool RenderText::containsCaretOffset(unsigned offset) const
{
    if (auto* layout = simpleLineLayout())
        return SimpleLineLayout::containsCaretOffset(*this, *layout, offset);
    return m_lineBoxes.containsOffset(*this, offset, RenderTextLineBoxes::CaretOffset);
}

bool RenderText::hasRenderedText() const
{
    if (auto* layout = simpleLineLayout())
        return SimpleLineLayout::isTextRendered(*this, *layout);
    return m_lineBoxes.hasRenderedText();
}

int RenderText::previousOffset(int current) const
{
    if (isAllASCII() || m_text.is8Bit())
        return current - 1;

    StringImpl* textImpl = m_text.impl();
    UBreakIterator* iterator = cursorMovementIterator(StringView(textImpl->characters16(), textImpl->length()));
    if (!iterator)
        return current - 1;

    long result = ubrk_preceding(iterator, current);
    if (result == UBRK_DONE)
        result = current - 1;


    return result;
}

#if PLATFORM(COCOA) || PLATFORM(GTK)

const UChar hangulChoseongStart = 0x1100;
const UChar hangulChoseongEnd = 0x115F;
const UChar hangulJungseongStart = 0x1160;
const UChar hangulJungseongEnd = 0x11A2;
const UChar hangulJongseongStart = 0x11A8;
const UChar hangulJongseongEnd = 0x11F9;
const UChar hangulSyllableStart = 0xAC00;
const UChar hangulSyllableEnd = 0xD7AF;
const UChar hangulJongseongCount = 28;

enum class HangulState { L, V, T, LV, LVT, Break };

static inline bool isHangulLVT(UChar character)
{
    return (character - hangulSyllableStart) % hangulJongseongCount;
}

static inline bool isMark(UChar32 character)
{
    return U_GET_GC_MASK(character) & U_GC_M_MASK;
}

static inline bool isRegionalIndicator(UChar32 character)
{
    // National flag emoji each consists of a pair of regional indicator symbols.
    return 0x1F1E6 <= character && character <= 0x1F1FF;
}

static inline bool isInArmenianToLimbuRange(UChar32 character)
{
    return character >= 0x0530 && character < 0x1950;
}

#endif

int RenderText::previousOffsetForBackwardDeletion(int current) const
{
    ASSERT(!m_text.isNull());
    StringImpl& text = *m_text.impl();

    // FIXME: Unclear why this has so much handrolled code rather than using UBreakIterator.
    // Also unclear why this is so different from advanceByCombiningCharacterSequence.

    // FIXME: Seems like this fancier case could be used on all platforms now, no
    // need for the #else case below.
#if PLATFORM(COCOA) || PLATFORM(GTK)
    bool sawRegionalIndicator = false;
    bool sawEmojiGroupCandidate = false;
    bool sawEmojiFitzpatrickModifier = false;
    
    while (current > 0) {
        UChar32 character;
        U16_PREV(text, 0, current, character);

        if (sawEmojiGroupCandidate) {
            sawEmojiGroupCandidate = false;
            if (character == zeroWidthJoiner)
                continue;
            // We could have two emoji group candidates without a joiner in between.
            // Those should not be treated as a group.
            U16_FWD_1_UNSAFE(text, current);
            break;
        }

        if (sawEmojiFitzpatrickModifier) {
            if (isEmojiFitzpatrickModifier(character)) {
                // Don't treat two emoji modifiers in a row as a group.
                U16_FWD_1_UNSAFE(text, current);
                break;
            }
            if (!isVariationSelector(character))
                break;
        }

        if (sawRegionalIndicator) {
            // We don't check if the pair of regional indicator symbols before current position can actually be combined
            // into a flag, and just delete it. This may not agree with how the pair is rendered in edge cases,
            // but is good enough in practice.
            if (isRegionalIndicator(character))
                break;
            // Don't delete a preceding character that isn't a regional indicator symbol.
            U16_FWD_1_UNSAFE(text, current);
        }

        // We don't combine characters in Armenian ... Limbu range for backward deletion.
        if (isInArmenianToLimbuRange(character))
            break;

        if (isRegionalIndicator(character)) {
            sawRegionalIndicator = true;
            continue;
        }
        
        if (isEmojiFitzpatrickModifier(character)) {
            sawEmojiFitzpatrickModifier = true;
            continue;
        }

        if (isEmojiGroupCandidate(character)) {
            sawEmojiGroupCandidate = true;
            continue;
        }

        // FIXME: Why are FF9E and FF9F special cased here?
        if (!isMark(character) && character != 0xFF9E && character != 0xFF9F)
            break;
    }

    if (current <= 0)
        return current;

    // Hangul
    UChar character = text[current];
    if ((character >= hangulChoseongStart && character <= hangulJongseongEnd) || (character >= hangulSyllableStart && character <= hangulSyllableEnd)) {
        HangulState state;

        if (character < hangulJungseongStart)
            state = HangulState::L;
        else if (character < hangulJongseongStart)
            state = HangulState::V;
        else if (character < hangulSyllableStart)
            state = HangulState::T;
        else
            state = isHangulLVT(character) ? HangulState::LVT : HangulState::LV;

        while (current > 0 && (character = text[current - 1]) >= hangulChoseongStart && character <= hangulSyllableEnd && (character <= hangulJongseongEnd || character >= hangulSyllableStart)) {
            switch (state) {
            case HangulState::V:
                if (character <= hangulChoseongEnd)
                    state = HangulState::L;
                else if (character >= hangulSyllableStart && character <= hangulSyllableEnd && !isHangulLVT(character))
                    state = HangulState::LV;
                else if (character > hangulJungseongEnd)
                    state = HangulState::Break;
                break;
            case HangulState::T:
                if (character >= hangulJungseongStart && character <= hangulJungseongEnd)
                    state = HangulState::V;
                else if (character >= hangulSyllableStart && character <= hangulSyllableEnd)
                    state = isHangulLVT(character) ? HangulState::LVT : HangulState::LV;
                else if (character < hangulJungseongStart)
                    state = HangulState::Break;
                break;
            default:
                state = (character < hangulJungseongStart) ? HangulState::L : HangulState::Break;
                break;
            }
            if (state == HangulState::Break)
                break;
            --current;
        }
    }

    return current;
#else
    U16_BACK_1(text, 0, current);
    return current;
#endif
}

int RenderText::nextOffset(int current) const
{
    if (isAllASCII() || m_text.is8Bit())
        return current + 1;

    StringImpl* textImpl = m_text.impl();
    UBreakIterator* iterator = cursorMovementIterator(StringView(textImpl->characters16(), textImpl->length()));
    if (!iterator)
        return current + 1;

    long result = ubrk_following(iterator, current);
    if (result == UBRK_DONE)
        result = current + 1;

    return result;
}

bool RenderText::computeCanUseSimpleFontCodePath() const
{
    if (isAllASCII() || m_text.is8Bit())
        return true;
    return FontCascade::characterRangeCodePath(characters16(), length()) == FontCascade::Simple;
}

void RenderText::momentarilyRevealLastTypedCharacter(unsigned offsetAfterLastTypedCharacter)
{
    if (style().textSecurity() == TSNONE)
        return;
    auto& secureTextTimer = secureTextTimers().add(this, nullptr).iterator->value;
    if (!secureTextTimer)
        secureTextTimer = std::make_unique<SecureTextTimer>(*this);
    secureTextTimer->restart(offsetAfterLastTypedCharacter);
}

StringView RenderText::stringView(unsigned start, std::optional<unsigned> stop) const
{
    unsigned destination = stop.value_or(textLength());
    ASSERT(start <= length());
    ASSERT(destination <= length());
    ASSERT(start <= destination);
    if (is8Bit())
        return StringView(characters8() + start, destination - start);
    return StringView(characters16() + start, destination - start);
}

} // namespace WebCore