// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "sky/engine/core/rendering/RenderParagraph.h"

#include "sky/engine/core/rendering/BidiRunForLine.h"
#include "sky/engine/core/rendering/InlineIterator.h"
#include "sky/engine/core/rendering/RenderLayer.h"
#include "sky/engine/core/rendering/RenderObjectInlines.h"
#include "sky/engine/core/rendering/RenderView.h"
#include "sky/engine/core/rendering/TextRunConstructor.h"
#include "sky/engine/core/rendering/VerticalPositionCache.h"
#include "sky/engine/core/rendering/line/BreakingContextInlineHeaders.h"
#include "sky/engine/core/rendering/line/LineLayoutState.h"
#include "sky/engine/core/rendering/line/LineWidth.h"
#include "sky/engine/core/rendering/line/RenderTextInfo.h"
#include "sky/engine/core/rendering/line/WordMeasurement.h"
#include "sky/engine/platform/fonts/Character.h"
#include "sky/engine/platform/text/BidiResolver.h"
#include "sky/engine/wtf/RefCountedLeakCounter.h"
#include "sky/engine/wtf/StdLibExtras.h"
#include "sky/engine/wtf/Vector.h"
#include "sky/engine/wtf/unicode/CharacterNames.h"


namespace blink {

using namespace WTF::Unicode;

RenderParagraph::RenderParagraph()
{
}

RenderParagraph::~RenderParagraph()
{
}

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

LayoutUnit RenderParagraph::logicalLeftSelectionOffset(RenderBlock* rootBlock, LayoutUnit position)
{
    LayoutUnit logicalLeft = logicalLeftOffsetForLine(false);
    if (logicalLeft == logicalLeftOffsetForContent())
        return RenderBlock::logicalLeftSelectionOffset(rootBlock, position);

    RenderBlock* cb = this;
    while (cb != rootBlock) {
        logicalLeft += cb->logicalLeft();
        cb = cb->containingBlock();
    }
    return logicalLeft;
}

LayoutUnit RenderParagraph::logicalRightSelectionOffset(RenderBlock* rootBlock, LayoutUnit position)
{
    LayoutUnit logicalRight = logicalRightOffsetForLine(false);
    if (logicalRight == logicalRightOffsetForContent())
        return RenderBlock::logicalRightSelectionOffset(rootBlock, position);

    RenderBlock* cb = this;
    while (cb != rootBlock) {
        logicalRight += cb->logicalLeft();
        cb = cb->containingBlock();
    }
    return logicalRight;
}

RootInlineBox* RenderParagraph::lineAtIndex(int i) const
{
    ASSERT(i >= 0);

    for (RootInlineBox* box = firstRootBox(); box; box = box->nextRootBox()) {
        if (!i--)
            return box;
    }

    return 0;
}

int RenderParagraph::lineCount(const RootInlineBox* stopRootInlineBox, bool* found) const
{
    int count = 0;
    for (RootInlineBox* box = firstRootBox(); box; box = box->nextRootBox()) {
        count++;
        if (box == stopRootInlineBox) {
            if (found)
                *found = true;
            break;
        }
    }

    return count;
}

void RenderParagraph::deleteLineBoxTree()
{
    m_lineBoxes.deleteLineBoxTree();
}

GapRects RenderParagraph::inlineSelectionGaps(RenderBlock* rootBlock, const LayoutPoint& rootBlockPhysicalPosition, const LayoutSize& offsetFromRootBlock,
    LayoutUnit& lastLogicalTop, LayoutUnit& lastLogicalLeft, LayoutUnit& lastLogicalRight, const PaintInfo* paintInfo)
{
    GapRects result;

    bool containsStart = selectionState() == SelectionStart || selectionState() == SelectionBoth;

    if (!firstLineBox()) {
        if (containsStart) {
            // Go ahead and update our lastLogicalTop to be the bottom of the block.  <hr>s or empty blocks with height can trip this
            // case.
            lastLogicalTop = rootBlock->blockDirectionOffset(offsetFromRootBlock) + logicalHeight();
            lastLogicalLeft = logicalLeftSelectionOffset(rootBlock, logicalHeight());
            lastLogicalRight = logicalRightSelectionOffset(rootBlock, logicalHeight());
        }
        return result;
    }

    RootInlineBox* lastSelectedLine = 0;
    RootInlineBox* curr;
    for (curr = firstRootBox(); curr && !curr->hasSelectedChildren(); curr = curr->nextRootBox()) { }

    // Now paint the gaps for the lines.
    for (; curr && curr->hasSelectedChildren(); curr = curr->nextRootBox()) {
        LayoutUnit selTop =  curr->selectionTopAdjustedForPrecedingBlock();
        LayoutUnit selHeight = curr->selectionHeightAdjustedForPrecedingBlock();

        if (!containsStart && !lastSelectedLine && selectionState() != SelectionStart && selectionState() != SelectionBoth) {
            result.uniteCenter(blockSelectionGap(rootBlock, rootBlockPhysicalPosition, offsetFromRootBlock, lastLogicalTop,
                lastLogicalLeft, lastLogicalRight, selTop, paintInfo));
        }

        LayoutRect logicalRect(curr->logicalLeft(), selTop, curr->logicalWidth(), selTop + selHeight);
        logicalRect.move(offsetFromRootBlock);
        LayoutRect physicalRect = rootBlock->logicalRectToPhysicalRect(rootBlockPhysicalPosition, logicalRect);
        if (!paintInfo || (physicalRect.y() < paintInfo->rect.maxY() && physicalRect.maxY() > paintInfo->rect.y()))
            result.unite(curr->lineSelectionGap(rootBlock, rootBlockPhysicalPosition, offsetFromRootBlock, selTop, selHeight, paintInfo));

        lastSelectedLine = curr;
    }

    if (containsStart && !lastSelectedLine) {
        // VisibleSelection must start just after our last line.
        lastSelectedLine = lastRootBox();
    }

    if (lastSelectedLine && selectionState() != SelectionEnd && selectionState() != SelectionBoth) {
        // Go ahead and update our lastY to be the bottom of the last selected line.
        lastLogicalTop = rootBlock->blockDirectionOffset(offsetFromRootBlock) + lastSelectedLine->selectionBottom();
        lastLogicalLeft = logicalLeftSelectionOffset(rootBlock, lastSelectedLine->selectionBottom());
        lastLogicalRight = logicalRightSelectionOffset(rootBlock, lastSelectedLine->selectionBottom());
    }
    return result;
}

void RenderParagraph::addOverflowFromChildren()
{
    LayoutUnit endPadding = hasOverflowClip() ? paddingEnd() : LayoutUnit();
    for (RootInlineBox* curr = firstRootBox(); curr; curr = curr->nextRootBox()) {
        addLayoutOverflow(curr->paddedLayoutOverflowRect(endPadding));
        LayoutRect visualOverflow = curr->visualOverflowRect(curr->lineTop(), curr->lineBottom());
        addContentsVisualOverflow(visualOverflow);
    }
}

void RenderParagraph::simplifiedNormalFlowLayout()
{
      ListHashSet<RootInlineBox*> lineBoxes;
      for (InlineWalker walker(this); !walker.atEnd(); walker.advance()) {
          RenderObject* o = walker.current();
          if (!o->isOutOfFlowPositioned() && o->isReplaced()) {
              o->layoutIfNeeded();
              if (toRenderBox(o)->inlineBoxWrapper()) {
                  RootInlineBox& box = toRenderBox(o)->inlineBoxWrapper()->root();
                  lineBoxes.add(&box);
              }
          } else if (o->isText() || (o->isRenderInline() && !walker.atEndOfInline())) {
              o->clearNeedsLayout();
          }
      }

      // FIXME: Glyph overflow will get lost in this case, but not really a big deal.
      GlyphOverflowAndFallbackFontsMap textBoxDataMap;
      for (ListHashSet<RootInlineBox*>::const_iterator it = lineBoxes.begin(); it != lineBoxes.end(); ++it) {
          RootInlineBox* box = *it;
          box->computeOverflow(box->lineTop(), box->lineBottom(), textBoxDataMap);
      }
}

void RenderParagraph::paintChildren(PaintInfo& paintInfo, const LayoutPoint& paintOffset, Vector<RenderBox*>& layers)
{
    m_lineBoxes.paint(this, paintInfo, paintOffset, layers);

    for (RenderObject* child = firstChild(); child; child = child->nextSibling()) {
        // TODO(ojan): This is wrong at the moment. Inlines can have self painting
        // layers as well. Either make inlines with self-painting layers work or
        // don't allow inlines to be self painting.
        if (child->isBox()) {
            RenderBox* box = toRenderBox(child);
            if (box->hasSelfPaintingLayer())
                layers.append(box);
        }
    }
}

bool RenderParagraph::hitTestContents(const HitTestRequest& request, HitTestResult& result, const HitTestLocation& locationInContainer, const LayoutPoint& accumulatedOffset)
{
    return m_lineBoxes.hitTest(this, request, result, locationInContainer, accumulatedOffset);
}

void RenderParagraph::markLinesDirtyInBlockRange(LayoutUnit logicalTop, LayoutUnit logicalBottom, RootInlineBox* highest)
{
    if (logicalTop >= logicalBottom)
        return;

    RootInlineBox* lowestDirtyLine = lastRootBox();
    RootInlineBox* afterLowest = lowestDirtyLine;
    while (lowestDirtyLine && lowestDirtyLine->lineBottomWithLeading() >= logicalBottom && logicalBottom < LayoutUnit::max()) {
        afterLowest = lowestDirtyLine;
        lowestDirtyLine = lowestDirtyLine->prevRootBox();
    }

    while (afterLowest && afterLowest != highest && (afterLowest->lineBottomWithLeading() >= logicalTop || afterLowest->lineBottomWithLeading() < 0)) {
        afterLowest->markDirty();
        afterLowest = afterLowest->prevRootBox();
    }
}

static void updateLogicalWidthForLeftAlignedBlock(bool isLeftToRightDirection, BidiRun* trailingSpaceRun, float& logicalLeft, float& totalLogicalWidth, float availableLogicalWidth)
{
    // The direction of the block should determine what happens with wide lines.
    // In particular with RTL blocks, wide lines should still spill out to the left.
    if (isLeftToRightDirection) {
        if (totalLogicalWidth > availableLogicalWidth && trailingSpaceRun)
            trailingSpaceRun->m_box->setLogicalWidth(std::max<float>(0, trailingSpaceRun->m_box->logicalWidth() - totalLogicalWidth + availableLogicalWidth));
        return;
    }

    if (trailingSpaceRun)
        trailingSpaceRun->m_box->setLogicalWidth(0);
    else if (totalLogicalWidth > availableLogicalWidth)
        logicalLeft -= (totalLogicalWidth - availableLogicalWidth);
}

static void updateLogicalWidthForRightAlignedBlock(bool isLeftToRightDirection, BidiRun* trailingSpaceRun, float& logicalLeft, float& totalLogicalWidth, float availableLogicalWidth)
{
    // Wide lines spill out of the block based off direction.
    // So even if text-align is right, if direction is LTR, wide lines should overflow out of the right
    // side of the block.
    if (isLeftToRightDirection) {
        if (trailingSpaceRun) {
            totalLogicalWidth -= trailingSpaceRun->m_box->logicalWidth();
            trailingSpaceRun->m_box->setLogicalWidth(0);
        }
        if (totalLogicalWidth < availableLogicalWidth)
            logicalLeft += availableLogicalWidth - totalLogicalWidth;
        return;
    }

    if (totalLogicalWidth > availableLogicalWidth && trailingSpaceRun) {
        trailingSpaceRun->m_box->setLogicalWidth(std::max<float>(0, trailingSpaceRun->m_box->logicalWidth() - totalLogicalWidth + availableLogicalWidth));
        totalLogicalWidth -= trailingSpaceRun->m_box->logicalWidth();
    } else
        logicalLeft += availableLogicalWidth - totalLogicalWidth;
}

static void updateLogicalWidthForCenterAlignedBlock(bool isLeftToRightDirection, BidiRun* trailingSpaceRun, float& logicalLeft, float& totalLogicalWidth, float availableLogicalWidth)
{
    float trailingSpaceWidth = 0;
    if (trailingSpaceRun) {
        totalLogicalWidth -= trailingSpaceRun->m_box->logicalWidth();
        trailingSpaceWidth = std::min(trailingSpaceRun->m_box->logicalWidth(), (availableLogicalWidth - totalLogicalWidth + 1) / 2);
        trailingSpaceRun->m_box->setLogicalWidth(std::max<float>(0, trailingSpaceWidth));
    }
    if (isLeftToRightDirection)
        logicalLeft += std::max<float>((availableLogicalWidth - totalLogicalWidth) / 2, 0);
    else
        logicalLeft += totalLogicalWidth > availableLogicalWidth ? (availableLogicalWidth - totalLogicalWidth) : (availableLogicalWidth - totalLogicalWidth) / 2 - trailingSpaceWidth;
}

void RenderParagraph::updateLogicalWidthForAlignment(const ETextAlign& textAlign, const RootInlineBox* rootInlineBox, BidiRun* trailingSpaceRun, float& logicalLeft, float& totalLogicalWidth, float& availableLogicalWidth, unsigned expansionOpportunityCount)
{
    TextDirection direction;
    if (rootInlineBox && rootInlineBox->renderer().style()->unicodeBidi() == Plaintext)
        direction = rootInlineBox->direction();
    else
        direction = style()->direction();

    // Armed with the total width of the line (without justification),
    // we now examine our text-align property in order to determine where to position the
    // objects horizontally. The total width of the line can be increased if we end up
    // justifying text.
    switch (textAlign) {
    case LEFT:
        updateLogicalWidthForLeftAlignedBlock(style()->isLeftToRightDirection(), trailingSpaceRun, logicalLeft, totalLogicalWidth, availableLogicalWidth);
        break;
    case RIGHT:
        updateLogicalWidthForRightAlignedBlock(style()->isLeftToRightDirection(), trailingSpaceRun, logicalLeft, totalLogicalWidth, availableLogicalWidth);
        break;
    case CENTER:
        updateLogicalWidthForCenterAlignedBlock(style()->isLeftToRightDirection(), trailingSpaceRun, logicalLeft, totalLogicalWidth, availableLogicalWidth);
        break;
    case JUSTIFY:
        adjustInlineDirectionLineBounds(expansionOpportunityCount, logicalLeft, availableLogicalWidth);
        if (expansionOpportunityCount) {
            if (trailingSpaceRun) {
                totalLogicalWidth -= trailingSpaceRun->m_box->logicalWidth();
                trailingSpaceRun->m_box->setLogicalWidth(0);
            }
            break;
        }
        // Fall through
    case TASTART:
        if (direction == LTR)
            updateLogicalWidthForLeftAlignedBlock(style()->isLeftToRightDirection(), trailingSpaceRun, logicalLeft, totalLogicalWidth, availableLogicalWidth);
        else
            updateLogicalWidthForRightAlignedBlock(style()->isLeftToRightDirection(), trailingSpaceRun, logicalLeft, totalLogicalWidth, availableLogicalWidth);
        break;
    case TAEND:
        if (direction == LTR)
            updateLogicalWidthForRightAlignedBlock(style()->isLeftToRightDirection(), trailingSpaceRun, logicalLeft, totalLogicalWidth, availableLogicalWidth);
        else
            updateLogicalWidthForLeftAlignedBlock(style()->isLeftToRightDirection(), trailingSpaceRun, logicalLeft, totalLogicalWidth, availableLogicalWidth);
        break;
    }
}

RootInlineBox* RenderParagraph::createAndAppendRootInlineBox()
{
    RootInlineBox* rootBox = createRootInlineBox();
    m_lineBoxes.appendLineBox(rootBox);
    return rootBox;
}

RootInlineBox* RenderParagraph::createRootInlineBox()
{
    return new RootInlineBox(*this);
}

InlineBox* RenderParagraph::createInlineBoxForRenderer(RenderObject* obj, bool isRootLineBox, bool isOnlyRun)
{
    if (isRootLineBox)
        return toRenderParagraph(obj)->createAndAppendRootInlineBox();

    if (obj->isText()) {
        InlineTextBox* textBox = toRenderText(obj)->createInlineTextBox();
        // We only treat a box as text for a <br> if we are on a line by ourself or in strict mode
        // (Note the use of strict mode.  In "almost strict" mode, we don't treat the box for <br> as text.)
        return textBox;
    }

    if (obj->isBox())
        return toRenderBox(obj)->createInlineBox();

    return toRenderInline(obj)->createAndAppendInlineFlowBox();
}

static inline void dirtyLineBoxesForRenderer(RenderObject* o, bool fullLayout)
{
    if (o->isText()) {
        RenderText* renderText = toRenderText(o);
        renderText->dirtyLineBoxes(fullLayout);
    } else
        toRenderInline(o)->dirtyLineBoxes(fullLayout);
}

static bool parentIsConstructedOrHaveNext(InlineFlowBox* parentBox)
{
    do {
        if (parentBox->isConstructed() || parentBox->nextOnLine())
            return true;
        parentBox = parentBox->parent();
    } while (parentBox);
    return false;
}

InlineFlowBox* RenderParagraph::createLineBoxes(RenderObject* obj, const LineInfo& lineInfo, InlineBox* childBox)
{
    // See if we have an unconstructed line box for this object that is also
    // the last item on the line.
    unsigned lineDepth = 1;
    InlineFlowBox* parentBox = 0;
    InlineFlowBox* result = 0;
    bool hasDefaultLineBoxContain = style()->lineBoxContain() == RenderStyle::initialLineBoxContain();
    do {
        ASSERT_WITH_SECURITY_IMPLICATION(obj->isRenderInline() || obj == this);

        RenderInline* inlineFlow = (obj != this) ? toRenderInline(obj) : 0;

        // Get the last box we made for this render object.
        parentBox = inlineFlow ? inlineFlow->lastLineBox() : toRenderBlock(obj)->lastLineBox();

        // If this box or its ancestor is constructed then it is from a previous line, and we need
        // to make a new box for our line.  If this box or its ancestor is unconstructed but it has
        // something following it on the line, then we know we have to make a new box
        // as well.  In this situation our inline has actually been split in two on
        // the same line (this can happen with very fancy language mixtures).
        bool constructedNewBox = false;
        bool allowedToConstructNewBox = !hasDefaultLineBoxContain || !inlineFlow || inlineFlow->alwaysCreateLineBoxes();
        bool canUseExistingParentBox = parentBox && !parentIsConstructedOrHaveNext(parentBox);
        if (allowedToConstructNewBox && !canUseExistingParentBox) {
            // We need to make a new box for this render object.  Once
            // made, we need to place it at the end of the current line.
            InlineBox* newBox = createInlineBoxForRenderer(obj, obj == this);
            ASSERT_WITH_SECURITY_IMPLICATION(newBox->isInlineFlowBox());
            parentBox = toInlineFlowBox(newBox);
            parentBox->setFirstLineStyleBit(lineInfo.isFirstLine());
            if (!hasDefaultLineBoxContain)
                parentBox->clearDescendantsHaveSameLineHeightAndBaseline();
            constructedNewBox = true;
        }

        if (constructedNewBox || canUseExistingParentBox) {
            if (!result)
                result = parentBox;

            // If we have hit the block itself, then |box| represents the root
            // inline box for the line, and it doesn't have to be appended to any parent
            // inline.
            if (childBox)
                parentBox->addToLine(childBox);

            if (!constructedNewBox || obj == this)
                break;

            childBox = parentBox;
        }

        // If we've exceeded our line depth, then jump straight to the root and skip all the remaining
        // intermediate inline flows.
        obj = (++lineDepth >= cMaxLineDepth) ? this : obj->parent();

    } while (true);

    return result;
}

template <typename CharacterType>
static inline bool endsWithASCIISpaces(const CharacterType* characters, unsigned pos, unsigned end)
{
    while (isASCIISpace(characters[pos])) {
        pos++;
        if (pos >= end)
            return true;
    }
    return false;
}

static bool reachedEndOfTextRenderer(const BidiRunList<BidiRun>& bidiRuns)
{
    BidiRun* run = bidiRuns.logicallyLastRun();
    if (!run)
        return true;
    unsigned pos = run->stop();
    RenderObject* r = run->m_object;
    if (!r->isText())
        return false;
    RenderText* renderText = toRenderText(r);
    unsigned length = renderText->textLength();
    if (pos >= length)
        return true;

    if (renderText->is8Bit())
        return endsWithASCIISpaces(renderText->characters8(), pos, length);
    return endsWithASCIISpaces(renderText->characters16(), pos, length);
}

RootInlineBox* RenderParagraph::constructLine(BidiRunList<BidiRun>& bidiRuns, const LineInfo& lineInfo)
{
    ASSERT(bidiRuns.firstRun());

    bool rootHasSelectedChildren = false;
    InlineFlowBox* parentBox = 0;
    int runCount = bidiRuns.runCount() - lineInfo.runsFromLeadingWhitespace();
    for (BidiRun* r = bidiRuns.firstRun(); r; r = r->next()) {
        // Create a box for our object.
        bool isOnlyRun = (runCount == 1);
        if (runCount == 2)
            isOnlyRun = false;

        if (lineInfo.isEmpty())
            continue;

        InlineBox* box = createInlineBoxForRenderer(r->m_object, false, isOnlyRun);
        r->m_box = box;

        ASSERT(box);
        if (!box)
            continue;

        if (!rootHasSelectedChildren && box->renderer().selectionState() != RenderObject::SelectionNone)
            rootHasSelectedChildren = true;

        // If we have no parent box yet, or if the run is not simply a sibling,
        // then we need to construct inline boxes as necessary to properly enclose the
        // run's inline box. Segments can only be siblings at the root level, as
        // they are positioned separately.
        if (!parentBox || parentBox->renderer() != r->m_object->parent()) {
            // Create new inline boxes all the way back to the appropriate insertion point.
            parentBox = createLineBoxes(r->m_object->parent(), lineInfo, box);
        } else {
            // Append the inline box to this line.
            parentBox->addToLine(box);
        }

        box->setBidiLevel(r->level());

        if (box->isInlineTextBox()) {
            InlineTextBox* text = toInlineTextBox(box);
            text->setStart(r->m_start);
            text->setLen(r->m_stop - r->m_start);
            text->setDirOverride(r->dirOverride());
            if (r->m_hasHyphen)
                text->setHasHyphen(true);
        }
    }

    ASSERT(lastLineBox() && !lastLineBox()->isConstructed());

    // Set the m_selectedChildren flag on the root inline box if one of the leaf inline box
    // from the bidi runs walk above has a selection state.
    if (rootHasSelectedChildren)
        lastLineBox()->root().setHasSelectedChildren(true);

    // Set bits on our inline flow boxes that indicate which sides should
    // paint borders/margins/padding.  This knowledge will ultimately be used when
    // we determine the horizontal positions and widths of all the inline boxes on
    // the line.
    bool isLogicallyLastRunWrapped = bidiRuns.logicallyLastRun()->m_object && bidiRuns.logicallyLastRun()->m_object->isText() ? !reachedEndOfTextRenderer(bidiRuns) : true;
    lastLineBox()->determineSpacingForFlowBoxes(lineInfo.isLastLine(), isLogicallyLastRunWrapped, bidiRuns.logicallyLastRun()->m_object);

    // Now mark the line boxes as being constructed.
    lastLineBox()->setConstructed();

    // Return the last line.
    return lastRootBox();
}

ETextAlign RenderParagraph::textAlignmentForLine(bool endsWithSoftBreak) const
{
    ETextAlign alignment = style()->textAlign();
    if (endsWithSoftBreak)
        return alignment;
    return (alignment == JUSTIFY) ? TASTART : alignment;
}

static inline void setLogicalWidthForTextRun(RootInlineBox* lineBox, BidiRun* run, RenderText* renderer, float xPos, const LineInfo& lineInfo,
                                             GlyphOverflowAndFallbackFontsMap& textBoxDataMap, VerticalPositionCache& verticalPositionCache, WordMeasurements& wordMeasurements)
{
    HashSet<const SimpleFontData*> fallbackFonts;
    GlyphOverflow glyphOverflow;

    const Font& font = renderer->style(lineInfo.isFirstLine())->font();
    // Always compute glyph overflow if the block's line-box-contain value is "glyphs".
    if (lineBox->fitsToGlyphs()) {
        // If we don't stick out of the root line's font box, then don't bother computing our glyph overflow. This optimization
        // will keep us from computing glyph bounds in nearly all cases.
        bool includeRootLine = lineBox->includesRootLineBoxFontOrLeading();
        int baselineShift = lineBox->verticalPositionForBox(run->m_box, verticalPositionCache);
        int rootDescent = includeRootLine ? font.fontMetrics().descent() : 0;
        int rootAscent = includeRootLine ? font.fontMetrics().ascent() : 0;
        int boxAscent = font.fontMetrics().ascent() - baselineShift;
        int boxDescent = font.fontMetrics().descent() + baselineShift;
        if (boxAscent > rootDescent ||  boxDescent > rootAscent)
            glyphOverflow.computeBounds = true;
    }

    LayoutUnit hyphenWidth = 0;
    if (toInlineTextBox(run->m_box)->hasHyphen()) {
        const Font& font = renderer->style(lineInfo.isFirstLine())->font();
        hyphenWidth = measureHyphenWidth(renderer, font, run->direction());
    }
    float measuredWidth = 0;

    bool kerningIsEnabled = font.fontDescription().typesettingFeatures() & Kerning;

    bool canUseSimpleFontCodePath = renderer->canUseSimpleFontCodePath();

    // Since we don't cache glyph overflows, we need to re-measure the run if
    // the style is linebox-contain: glyph.

    if (!lineBox->fitsToGlyphs() && canUseSimpleFontCodePath) {
        int lastEndOffset = run->m_start;
        for (size_t i = 0, size = wordMeasurements.size(); i < size && lastEndOffset < run->m_stop; ++i) {
            const WordMeasurement& wordMeasurement = wordMeasurements[i];
            if (wordMeasurement.width <=0 || wordMeasurement.startOffset == wordMeasurement.endOffset)
                continue;
            if (wordMeasurement.renderer != renderer || wordMeasurement.startOffset != lastEndOffset || wordMeasurement.endOffset > run->m_stop)
                continue;

            lastEndOffset = wordMeasurement.endOffset;
            if (kerningIsEnabled && lastEndOffset == run->m_stop) {
                int wordLength = lastEndOffset - wordMeasurement.startOffset;
                measuredWidth += renderer->width(wordMeasurement.startOffset, wordLength, xPos, run->direction(), lineInfo.isFirstLine());
                if (i > 0 && wordLength == 1 && renderer->characterAt(wordMeasurement.startOffset) == ' ')
                    measuredWidth += renderer->style()->wordSpacing();
            } else
                measuredWidth += wordMeasurement.width;
            if (!wordMeasurement.fallbackFonts.isEmpty()) {
                HashSet<const SimpleFontData*>::const_iterator end = wordMeasurement.fallbackFonts.end();
                for (HashSet<const SimpleFontData*>::const_iterator it = wordMeasurement.fallbackFonts.begin(); it != end; ++it)
                    fallbackFonts.add(*it);
            }
        }
        if (measuredWidth && lastEndOffset != run->m_stop) {
            // If we don't have enough cached data, we'll measure the run again.
            measuredWidth = 0;
            fallbackFonts.clear();
        }
    }

    if (!measuredWidth)
        measuredWidth = renderer->width(run->m_start, run->m_stop - run->m_start, xPos, run->direction(), lineInfo.isFirstLine(), &fallbackFonts, &glyphOverflow);

    run->m_box->setLogicalWidth(measuredWidth + hyphenWidth);
    if (!fallbackFonts.isEmpty()) {
        ASSERT(run->m_box->isText());
        GlyphOverflowAndFallbackFontsMap::ValueType* it = textBoxDataMap.add(toInlineTextBox(run->m_box), std::make_pair(Vector<const SimpleFontData*>(), GlyphOverflow())).storedValue;
        ASSERT(it->value.first.isEmpty());
        copyToVector(fallbackFonts, it->value.first);
        run->m_box->parent()->clearDescendantsHaveSameLineHeightAndBaseline();
    }
    if (!glyphOverflow.isZero()) {
        ASSERT(run->m_box->isText());
        GlyphOverflowAndFallbackFontsMap::ValueType* it = textBoxDataMap.add(toInlineTextBox(run->m_box), std::make_pair(Vector<const SimpleFontData*>(), GlyphOverflow())).storedValue;
        it->value.second = glyphOverflow;
        run->m_box->clearKnownToHaveNoOverflow();
    }
}

static inline void computeExpansionForJustifiedText(BidiRun* firstRun, BidiRun* trailingSpaceRun, Vector<unsigned, 16>& expansionOpportunities, unsigned expansionOpportunityCount, float& totalLogicalWidth, float availableLogicalWidth)
{
    if (!expansionOpportunityCount || availableLogicalWidth <= totalLogicalWidth)
        return;

    size_t i = 0;
    for (BidiRun* r = firstRun; r; r = r->next()) {
        if (!r->m_box || r == trailingSpaceRun)
            continue;

        if (r->m_object->isText()) {
            unsigned opportunitiesInRun = expansionOpportunities[i++];

            ASSERT(opportunitiesInRun <= expansionOpportunityCount);

            // Don't justify for white-space: pre.
            if (r->m_object->style()->whiteSpace() != PRE) {
                InlineTextBox* textBox = toInlineTextBox(r->m_box);
                int expansion = (availableLogicalWidth - totalLogicalWidth) * opportunitiesInRun / expansionOpportunityCount;
                textBox->setExpansion(expansion);
                totalLogicalWidth += expansion;
            }
            expansionOpportunityCount -= opportunitiesInRun;
            if (!expansionOpportunityCount)
                break;
        }
    }
}

static void updateLogicalInlinePositions(RenderParagraph* block, float& lineLogicalLeft, float& lineLogicalRight, float& availableLogicalWidth, IndentTextOrNot shouldIndentText)
{
    lineLogicalLeft = block->logicalLeftOffsetForLine(shouldIndentText == IndentText).toFloat();
    lineLogicalRight = block->logicalRightOffsetForLine(shouldIndentText == IndentText).toFloat();
    availableLogicalWidth = lineLogicalRight - lineLogicalLeft;
}

void RenderParagraph::computeInlineDirectionPositionsForLine(RootInlineBox* lineBox, const LineInfo& lineInfo, BidiRun* firstRun, BidiRun* trailingSpaceRun, bool reachedEnd,
                                                         GlyphOverflowAndFallbackFontsMap& textBoxDataMap, VerticalPositionCache& verticalPositionCache, WordMeasurements& wordMeasurements)
{
    ETextAlign textAlign = textAlignmentForLine(!reachedEnd && !lineBox->endsWithBreak());

    // CSS 2.1: "'Text-indent' only affects a line if it is the first formatted line of an element. For example, the first line of an anonymous block
    // box is only affected if it is the first child of its parent element."
    // CSS3 "text-indent", "each-line" affects the first line of the block container as well as each line after a forced line break,
    // but does not affect lines after a soft wrap break.
    bool isFirstLine = lineInfo.isFirstLine();
    bool isAfterHardLineBreak = lineBox->prevRootBox() && lineBox->prevRootBox()->endsWithBreak();
    IndentTextOrNot shouldIndentText = requiresIndent(isFirstLine, isAfterHardLineBreak, style());
    float lineLogicalLeft;
    float lineLogicalRight;
    float availableLogicalWidth;
    updateLogicalInlinePositions(this, lineLogicalLeft, lineLogicalRight, availableLogicalWidth, shouldIndentText);
    bool needsWordSpacing;

    if (firstRun && firstRun->m_object->isReplaced())
        updateLogicalInlinePositions(this, lineLogicalLeft, lineLogicalRight, availableLogicalWidth, shouldIndentText);

    computeInlineDirectionPositionsForSegment(lineBox, lineInfo, textAlign, lineLogicalLeft, availableLogicalWidth, firstRun, trailingSpaceRun, textBoxDataMap, verticalPositionCache, wordMeasurements);
    // The widths of all runs are now known. We can now place every inline box (and
    // compute accurate widths for the inline flow boxes).
    needsWordSpacing = false;
    lineBox->placeBoxesInInlineDirection(lineLogicalLeft, needsWordSpacing);
}

BidiRun* RenderParagraph::computeInlineDirectionPositionsForSegment(RootInlineBox* lineBox, const LineInfo& lineInfo, ETextAlign textAlign, float& logicalLeft,
    float& availableLogicalWidth, BidiRun* firstRun, BidiRun* trailingSpaceRun, GlyphOverflowAndFallbackFontsMap& textBoxDataMap, VerticalPositionCache& verticalPositionCache,
    WordMeasurements& wordMeasurements)
{
    bool needsWordSpacing = true;
    float totalLogicalWidth = lineBox->getFlowSpacingLogicalWidth().toFloat();
    unsigned expansionOpportunityCount = 0;
    bool isAfterExpansion = true;
    Vector<unsigned, 16> expansionOpportunities;
    RenderObject* previousObject = 0;
    TextJustify textJustify = style()->textJustify();

    BidiRun* r = firstRun;
    for (; r; r = r->next()) {
        if (!r->m_box || r->m_object->isOutOfFlowPositioned() || r->m_box->isLineBreak())
            continue; // Positioned objects are only participating to figure out their
                      // correct static x position.  They have no effect on the width.
                      // Similarly, line break boxes have no effect on the width.
        if (r->m_object->isText()) {
            RenderText* rt = toRenderText(r->m_object);
            if (textAlign == JUSTIFY && r != trailingSpaceRun && textJustify != TextJustifyNone) {
                if (!isAfterExpansion)
                    toInlineTextBox(r->m_box)->setCanHaveLeadingExpansion(true);
                unsigned opportunitiesInRun;
                if (rt->is8Bit())
                    opportunitiesInRun = Character::expansionOpportunityCount(rt->characters8() + r->m_start, r->m_stop - r->m_start, r->m_box->direction(), isAfterExpansion);
                else
                    opportunitiesInRun = Character::expansionOpportunityCount(rt->characters16() + r->m_start, r->m_stop - r->m_start, r->m_box->direction(), isAfterExpansion);
                expansionOpportunities.append(opportunitiesInRun);
                expansionOpportunityCount += opportunitiesInRun;
            }

            if (rt->textLength()) {
                if (!r->m_start && needsWordSpacing && isSpaceOrNewline(rt->characterAt(r->m_start)))
                    totalLogicalWidth += rt->style(lineInfo.isFirstLine())->font().fontDescription().wordSpacing();
                needsWordSpacing = !isSpaceOrNewline(rt->characterAt(r->m_stop - 1));
            }

            setLogicalWidthForTextRun(lineBox, r, rt, totalLogicalWidth, lineInfo, textBoxDataMap, verticalPositionCache, wordMeasurements);
        } else {
            isAfterExpansion = false;
            if (!r->m_object->isRenderInline()) {
                RenderBox* renderBox = toRenderBox(r->m_object);
                r->m_box->setLogicalWidth(logicalWidthForChild(renderBox).toFloat());
                totalLogicalWidth += marginStartForChild(renderBox) + marginEndForChild(renderBox);
            }
        }

        totalLogicalWidth += r->m_box->logicalWidth();
        previousObject = r->m_object;
    }

    if (isAfterExpansion && !expansionOpportunities.isEmpty()) {
        expansionOpportunities.last()--;
        expansionOpportunityCount--;
    }

    updateLogicalWidthForAlignment(textAlign, lineBox, trailingSpaceRun, logicalLeft, totalLogicalWidth, availableLogicalWidth, expansionOpportunityCount);

    computeExpansionForJustifiedText(firstRun, trailingSpaceRun, expansionOpportunities, expansionOpportunityCount, totalLogicalWidth, availableLogicalWidth);

    return r;
}

void RenderParagraph::computeBlockDirectionPositionsForLine(RootInlineBox* lineBox, BidiRun* firstRun, GlyphOverflowAndFallbackFontsMap& textBoxDataMap,
                                                        VerticalPositionCache& verticalPositionCache)
{
    setLogicalHeight(lineBox->alignBoxesInBlockDirection(logicalHeight(), textBoxDataMap, verticalPositionCache));

    // Now make sure we place replaced render objects correctly.
    for (BidiRun* r = firstRun; r; r = r->next()) {
        ASSERT(r->m_box);
        if (!r->m_box)
            continue; // Skip runs with no line boxes.

        // Align positioned boxes with the top of the line box.  This is
        // a reasonable approximation of an appropriate y position.
        if (r->m_object->isOutOfFlowPositioned())
            r->m_box->setLogicalTop(logicalHeight().toFloat());

        // Position is used to properly position both replaced elements and
        // to update the static normal flow x/y of positioned elements.
        if (r->m_object->isText())
            toRenderText(r->m_object)->positionLineBox(r->m_box);
        else if (r->m_object->isBox())
            toRenderBox(r->m_object)->positionLineBox(r->m_box);
    }
}

// This function constructs line boxes for all of the text runs in the resolver and computes their position.
RootInlineBox* RenderParagraph::createLineBoxesFromBidiRuns(unsigned bidiLevel, BidiRunList<BidiRun>& bidiRuns, const InlineIterator& end, LineInfo& lineInfo, VerticalPositionCache& verticalPositionCache, BidiRun* trailingSpaceRun, WordMeasurements& wordMeasurements)
{
    if (!bidiRuns.runCount())
        return 0;

    // FIXME: Why is this only done when we had runs?
    lineInfo.setLastLine(!end.object());

    RootInlineBox* lineBox = constructLine(bidiRuns, lineInfo);
    if (!lineBox)
        return 0;

    lineBox->setBidiLevel(bidiLevel);
    lineBox->setEndsWithBreak(lineInfo.previousLineBrokeCleanly());

    GlyphOverflowAndFallbackFontsMap textBoxDataMap;

    // Now we position all of our text runs horizontally.
    computeInlineDirectionPositionsForLine(lineBox, lineInfo, bidiRuns.firstRun(), trailingSpaceRun, end.atEnd(), textBoxDataMap, verticalPositionCache, wordMeasurements);

    // Now position our text runs vertically.
    computeBlockDirectionPositionsForLine(lineBox, bidiRuns.firstRun(), textBoxDataMap, verticalPositionCache);

    // Compute our overflow now.
    lineBox->computeOverflow(lineBox->lineTop(), lineBox->lineBottom(), textBoxDataMap);

    return lineBox;
}

static void deleteLineRange(LineLayoutState& layoutState, RootInlineBox* startLine, RootInlineBox* stopLine = 0)
{
    RootInlineBox* boxToDelete = startLine;
    while (boxToDelete && boxToDelete != stopLine) {
        // Note: deleteLineRange(firstRootBox()) is not identical to deleteLineBoxTree().
        // deleteLineBoxTree uses nextLineBox() instead of nextRootBox() when traversing.
        RootInlineBox* next = boxToDelete->nextRootBox();
        boxToDelete->deleteLine();
        boxToDelete = next;
    }
}

void RenderParagraph::layoutRunsAndFloats(LineLayoutState& layoutState)
{
    // We want to skip ahead to the first dirty line
    InlineBidiResolver resolver;
    RootInlineBox* startLine = determineStartPosition(layoutState, resolver);

    // We also find the first clean line and extract these lines.  We will add them back
    // if we determine that we're able to synchronize after handling all our dirty lines.
    InlineIterator cleanLineStart;
    BidiStatus cleanLineBidiStatus;
    if (!layoutState.isFullLayout() && startLine)
        determineEndPosition(layoutState, startLine, cleanLineStart, cleanLineBidiStatus);

    if (startLine)
        deleteLineRange(layoutState, startLine);

    layoutRunsAndFloatsInRange(layoutState, resolver, cleanLineStart, cleanLineBidiStatus);
    linkToEndLineIfNeeded(layoutState);
}

void RenderParagraph::layoutRunsAndFloatsInRange(LineLayoutState& layoutState,
    InlineBidiResolver& resolver, const InlineIterator& cleanLineStart,
    const BidiStatus& cleanLineBidiStatus)
{
    RenderStyle* styleToUse = style();
    LineMidpointState& lineMidpointState = resolver.midpointState();
    InlineIterator endOfLine = resolver.position();
    bool checkForEndLineMatch = layoutState.endLine();
    RenderTextInfo renderTextInfo;
    VerticalPositionCache verticalPositionCache;

    LineBreaker lineBreaker(this);

    while (!endOfLine.atEnd()) {
        // FIXME: Is this check necessary before the first iteration or can it be moved to the end?
        if (checkForEndLineMatch) {
            layoutState.setEndLineMatched(matchedEndLine(layoutState, resolver, cleanLineStart, cleanLineBidiStatus));
            if (layoutState.endLineMatched()) {
                resolver.setPosition(InlineIterator(resolver.position().root(), 0, 0), 0);
                break;
            }
        }

        lineMidpointState.reset();

        layoutState.lineInfo().setEmpty(true);
        layoutState.lineInfo().resetRunsFromLeadingWhitespace();

        bool isNewUBAParagraph = layoutState.lineInfo().previousLineBrokeCleanly();
        FloatingObject* lastFloatFromPreviousLine = 0;

        WordMeasurements wordMeasurements;
        endOfLine = lineBreaker.nextLineBreak(resolver, layoutState.lineInfo(), renderTextInfo,
            lastFloatFromPreviousLine, wordMeasurements);
        renderTextInfo.m_lineBreakIterator.resetPriorContext();
        if (resolver.position().atEnd()) {
            // FIXME: We shouldn't be creating any runs in nextLineBreak to begin with!
            // Once BidiRunList is separated from BidiResolver this will not be needed.
            resolver.runs().deleteRuns();
            resolver.markCurrentRunEmpty(); // FIXME: This can probably be replaced by an ASSERT (or just removed).
            resolver.setPosition(InlineIterator(resolver.position().root(), 0, 0), 0);
            break;
        }

        ASSERT(endOfLine != resolver.position());

        // This is a short-cut for empty lines.
        if (layoutState.lineInfo().isEmpty()) {
            if (lastRootBox())
                lastRootBox()->setLineBreakInfo(endOfLine.object(), endOfLine.offset(), resolver.status());
        } else {
            VisualDirectionOverride override = (styleToUse->rtlOrdering() == VisualOrder ? (styleToUse->direction() == LTR ? VisualLeftToRightOverride : VisualRightToLeftOverride) : NoVisualOverride);
            if (isNewUBAParagraph && styleToUse->unicodeBidi() == Plaintext && !resolver.context()->parent()) {
                TextDirection direction = determinePlaintextDirectionality(resolver.position().root(), resolver.position().object(), resolver.position().offset());
                resolver.setStatus(BidiStatus(direction, isOverride(styleToUse->unicodeBidi())));
            }
            // FIXME: This ownership is reversed. We should own the BidiRunList and pass it to createBidiRunsForLine.
            BidiRunList<BidiRun>& bidiRuns = resolver.runs();
            constructBidiRunsForLine(resolver, bidiRuns, endOfLine, override, layoutState.lineInfo().previousLineBrokeCleanly(), isNewUBAParagraph);
            ASSERT(resolver.position() == endOfLine);

            BidiRun* trailingSpaceRun = resolver.trailingSpaceRun();

            if (bidiRuns.runCount() && lineBreaker.lineWasHyphenated())
                bidiRuns.logicallyLastRun()->m_hasHyphen = true;

            // Now that the runs have been ordered, we create the line boxes.
            // At the same time we figure out where border/padding/margin should be applied for
            // inline flow boxes.

            RootInlineBox* lineBox = createLineBoxesFromBidiRuns(resolver.status().context->level(), bidiRuns, endOfLine, layoutState.lineInfo(), verticalPositionCache, trailingSpaceRun, wordMeasurements);

            bidiRuns.deleteRuns();
            resolver.markCurrentRunEmpty(); // FIXME: This can probably be replaced by an ASSERT (or just removed).

            if (lineBox)
                lineBox->setLineBreakInfo(endOfLine.object(), endOfLine.offset(), resolver.status());
        }

        if (!layoutState.lineInfo().isEmpty())
            layoutState.lineInfo().setFirstLine(false);

        lineMidpointState.reset();
        resolver.setPosition(endOfLine, numberOfIsolateAncestors(endOfLine));
    }
}

void RenderParagraph::linkToEndLineIfNeeded(LineLayoutState& layoutState)
{
    if (layoutState.endLine()) {
        if (layoutState.endLineMatched()) {
            // Attach all the remaining lines, and then adjust their y-positions as needed.
            LayoutUnit delta = logicalHeight() - layoutState.endLineLogicalTop();
            for (RootInlineBox* line = layoutState.endLine(); line; line = line->nextRootBox()) {
                line->attachLine();
                if (delta)
                    line->adjustBlockDirectionPosition(delta.toFloat());
            }
            setLogicalHeight(lastRootBox()->lineBottomWithLeading());
        } else {
            // Delete all the remaining lines.
            deleteLineRange(layoutState, layoutState.endLine());
        }
    }
}

struct InlineMinMaxIterator {
/* InlineMinMaxIterator is a class that will iterate over all render objects that contribute to
   inline min/max width calculations.  Note the following about the way it walks:
   (1) Positioned content is skipped (since it does not contribute to min/max width of a block)
   (2) We do not drill into the children of floats or replaced elements, since you can't break
       in the middle of such an element.
   (3) Inline flows (e.g., <a>, <span>, <i>) are walked twice, since each side can have
       distinct borders/margin/padding that contribute to the min/max width.
*/
    RenderObject* parent;
    RenderObject* current;
    bool endOfInline;

    InlineMinMaxIterator(RenderObject* p)
        : parent(p), current(p), endOfInline(false)
    {

    }

    RenderObject* next();
};

RenderObject* InlineMinMaxIterator::next()
{
    RenderObject* result = 0;
    bool oldEndOfInline = endOfInline;
    endOfInline = false;
    while (current || current == parent) {
        if (!oldEndOfInline && (current == parent || (!current->isReplaced() && !current->isOutOfFlowPositioned())))
            result = current->slowFirstChild();

        if (!result) {
            // We hit the end of our inline. (It was empty, e.g., <span></span>.)
            if (!oldEndOfInline && current->isRenderInline()) {
                result = current;
                endOfInline = true;
                break;
            }

            while (current && current != parent) {
                result = current->nextSibling();
                if (result)
                    break;
                current = current->parent();
                if (current && current != parent && current->isRenderInline()) {
                    result = current;
                    endOfInline = true;
                    break;
                }
            }
        }

        if (!result)
            break;

        if (!result->isOutOfFlowPositioned() && (result->isText() || result->isReplaced() || result->isRenderInline()))
            break;

        current = result;
        result = 0;
    }

    // Update our position.
    current = result;
    return current;
}

static LayoutUnit getBPMWidth(LayoutUnit childValue, Length cssUnit)
{
    if (cssUnit.type() != Auto)
        return (cssUnit.isFixed() ? static_cast<LayoutUnit>(cssUnit.value()) : childValue);
    return 0;
}

static LayoutUnit getBorderPaddingMargin(RenderBoxModelObject* child, bool endOfInline)
{
    RenderStyle* childStyle = child->style();
    if (endOfInline) {
        return getBPMWidth(child->marginEnd(), childStyle->marginEnd()) +
            getBPMWidth(child->paddingEnd(), childStyle->paddingEnd()) +
            child->borderEnd();
    }
    return getBPMWidth(child->marginStart(), childStyle->marginStart()) +
        getBPMWidth(child->paddingStart(), childStyle->paddingStart()) +
        child->borderStart();
}

static inline void stripTrailingSpace(float& inlineMax, float& inlineMin, RenderObject* trailingSpaceChild)
{
    if (trailingSpaceChild && trailingSpaceChild->isText()) {
        // Collapse away the trailing space at the end of a block.
        RenderText* t = toRenderText(trailingSpaceChild);
        const UChar space = ' ';
        const Font& font = t->style()->font(); // FIXME: This ignores first-line.
        float spaceWidth = font.width(constructTextRun(t, font, &space, 1, t->style(), LTR));
        inlineMax -= spaceWidth + font.fontDescription().wordSpacing();
        if (inlineMin > inlineMax)
            inlineMin = inlineMax;
    }
}

static inline void updatePreferredWidth(LayoutUnit& preferredWidth, float& result)
{
    LayoutUnit snappedResult = LayoutUnit::fromFloatCeil(result);
    preferredWidth = std::max(snappedResult, preferredWidth);
}

// When converting between floating point and LayoutUnits we risk losing precision
// with each conversion. When this occurs while accumulating our preferred widths,
// we can wind up with a line width that's larger than our maxPreferredWidth due to
// pure float accumulation.
static inline LayoutUnit adjustFloatForSubPixelLayout(float value)
{
    return LayoutUnit::fromFloatCeil(value);
}

// FIXME: This function should be broken into something less monolithic.
// FIXME: The main loop here is very similar to LineBreaker::nextSegmentBreak. They can probably reuse code.
void RenderParagraph::computeIntrinsicLogicalWidths(LayoutUnit& minLogicalWidth, LayoutUnit& maxLogicalWidth) const
{
    float inlineMax = 0;
    float inlineMin = 0;

    RenderStyle* styleToUse = style();
    RenderBlock* containingBlock = this->containingBlock();
    LayoutUnit cw = containingBlock ? containingBlock->contentLogicalWidth() : LayoutUnit();

    // If we are at the start of a line, we want to ignore all white-space.
    // Also strip spaces if we previously had text that ended in a trailing space.
    bool stripFrontSpaces = true;
    RenderObject* trailingSpaceChild = 0;

    bool autoWrap, oldAutoWrap;
    autoWrap = oldAutoWrap = styleToUse->autoWrap();

    InlineMinMaxIterator childIterator(const_cast<RenderParagraph*>(this));

    // Only gets added to the max preffered width once.
    bool addedTextIndent = false;
    // Signals the text indent was more negative than the min preferred width
    bool hasRemainingNegativeTextIndent = false;

    LayoutUnit textIndent = minimumValueForLength(styleToUse->textIndent(), cw);
    bool isPrevChildInlineFlow = false;
    bool shouldBreakLineAfterText = false;
    while (RenderObject* child = childIterator.next()) {
        autoWrap = child->isReplaced() ? child->parent()->style()->autoWrap() :
            child->style()->autoWrap();

        // Step One: determine whether or not we need to go ahead and
        // terminate our current line. Each discrete chunk can become
        // the new min-width, if it is the widest chunk seen so far, and
        // it can also become the max-width.

        // Children fall into three categories:
        // (1) An inline flow object. These objects always have a min/max of 0,
        // and are included in the iteration solely so that their margins can
        // be added in.
        //
        // (2) An inline non-text non-flow object, e.g., an inline replaced element.
        // These objects can always be on a line by themselves, so in this situation
        // we need to go ahead and break the current line, and then add in our own
        // margins and min/max width on its own line, and then terminate the line.
        //
        // (3) A text object. Text runs can have breakable characters at the start,
        // the middle or the end. They may also lose whitespace off the front if
        // we're already ignoring whitespace. In order to compute accurate min-width
        // information, we need three pieces of information.
        // (a) the min-width of the first non-breakable run. Should be 0 if the text string
        // starts with whitespace.
        // (b) the min-width of the last non-breakable run. Should be 0 if the text string
        // ends with whitespace.
        // (c) the min/max width of the string (trimmed for whitespace).
        //
        // If the text string starts with whitespace, then we need to go ahead and
        // terminate our current line (unless we're already in a whitespace stripping
        // mode.
        //
        // If the text string has a breakable character in the middle, but didn't start
        // with whitespace, then we add the width of the first non-breakable run and
        // then end the current line. We then need to use the intermediate min/max width
        // values (if any of them are larger than our current min/max). We then look at
        // the width of the last non-breakable run and use that to start a new line
        // (unless we end in whitespace).
        RenderStyle* childStyle = child->style();
        float childMin = 0;
        float childMax = 0;

        if (!child->isText()) {
            // Case (1) and (2). Inline replaced and inline flow elements.
            if (child->isRenderInline()) {
                // Add in padding/border/margin from the appropriate side of
                // the element.
                float bpm = getBorderPaddingMargin(toRenderInline(child), childIterator.endOfInline).toFloat();
                childMin += bpm;
                childMax += bpm;

                inlineMin += childMin;
                inlineMax += childMax;

                child->clearPreferredLogicalWidthsDirty();
            } else {
                // Inline replaced elts add in their margins to their min/max values.
                LayoutUnit margins = 0;
                Length startMargin = childStyle->marginStart();
                Length endMargin = childStyle->marginEnd();
                if (startMargin.isFixed())
                    margins += adjustFloatForSubPixelLayout(startMargin.value());
                if (endMargin.isFixed())
                    margins += adjustFloatForSubPixelLayout(endMargin.value());
                childMin += margins.ceilToFloat();
                childMax += margins.ceilToFloat();
            }
        }

        if (!child->isRenderInline() && !child->isText()) {
            // Case (2). Inline replaced elements and floats.
            // Go ahead and terminate the current line as far as
            // minwidth is concerned.
            LayoutUnit childMinPreferredLogicalWidth = child->minPreferredLogicalWidth();
            LayoutUnit childMaxPreferredLogicalWidth = child->maxPreferredLogicalWidth();
            childMin += childMinPreferredLogicalWidth.ceilToFloat();
            childMax += childMaxPreferredLogicalWidth.ceilToFloat();

            bool canBreakReplacedElement = true;
            if ((canBreakReplacedElement && (autoWrap || oldAutoWrap) && (!isPrevChildInlineFlow || shouldBreakLineAfterText))) {
                updatePreferredWidth(minLogicalWidth, inlineMin);
                inlineMin = 0;
            }

            // Add in text-indent. This is added in only once.
            if (!addedTextIndent) {
                float ceiledTextIndent = textIndent.ceilToFloat();
                childMin += ceiledTextIndent;
                childMax += ceiledTextIndent;

                if (childMin < 0)
                    textIndent = adjustFloatForSubPixelLayout(childMin);
                else
                    addedTextIndent = true;
            }

            // Add our width to the max.
            inlineMax += std::max<float>(0, childMax);

            if (!autoWrap || !canBreakReplacedElement || (isPrevChildInlineFlow && !shouldBreakLineAfterText)) {
                inlineMin += childMin;
            } else {
                // Now check our line.
                updatePreferredWidth(minLogicalWidth, childMin);

                // Now start a new line.
                inlineMin = 0;
            }

            if (autoWrap && canBreakReplacedElement && isPrevChildInlineFlow) {
                updatePreferredWidth(minLogicalWidth, inlineMin);
                inlineMin = 0;
            }

            // We are no longer stripping whitespace at the start of
            // a line.
            stripFrontSpaces = false;
            trailingSpaceChild = 0;
        } else if (child->isText()) {
            // Case (3). Text.
            RenderText* t = toRenderText(child);

            // Determine if we have a breakable character. Pass in
            // whether or not we should ignore any spaces at the front
            // of the string. If those are going to be stripped out,
            // then they shouldn't be considered in the breakable char
            // check.
            bool hasBreakableChar, hasBreak;
            float firstLineMinWidth, lastLineMinWidth;
            bool hasBreakableStart, hasBreakableEnd;
            float firstLineMaxWidth, lastLineMaxWidth;
            t->trimmedPrefWidths(inlineMax,
                firstLineMinWidth, hasBreakableStart, lastLineMinWidth, hasBreakableEnd,
                hasBreakableChar, hasBreak, firstLineMaxWidth, lastLineMaxWidth,
                childMin, childMax, stripFrontSpaces, styleToUse->direction());

            // This text object will not be rendered, but it may still provide a breaking opportunity.
            if (!hasBreak && !childMax) {
                if (autoWrap && (hasBreakableStart || hasBreakableEnd)) {
                    updatePreferredWidth(minLogicalWidth, inlineMin);
                    inlineMin = 0;
                }
                continue;
            }

            if (stripFrontSpaces)
                trailingSpaceChild = child;
            else
                trailingSpaceChild = 0;

            // Add in text-indent. This is added in only once.
            float ti = 0;
            if (!addedTextIndent || hasRemainingNegativeTextIndent) {
                ti = textIndent.ceilToFloat();
                childMin += ti;
                firstLineMinWidth += ti;

                // It the text indent negative and larger than the child minimum, we re-use the remainder
                // in future minimum calculations, but using the negative value again on the maximum
                // will lead to under-counting the max pref width.
                if (!addedTextIndent) {
                    childMax += ti;
                    firstLineMaxWidth += ti;
                    addedTextIndent = true;
                }

                if (childMin < 0) {
                    textIndent = childMin;
                    hasRemainingNegativeTextIndent = true;
                }
            }

            // If we have no breakable characters at all,
            // then this is the easy case. We add ourselves to the current
            // min and max and continue.
            if (!hasBreakableChar) {
                inlineMin += childMin;
            } else {
                if (hasBreakableStart) {
                    updatePreferredWidth(minLogicalWidth, inlineMin);
                } else {
                    inlineMin += firstLineMinWidth;
                    updatePreferredWidth(minLogicalWidth, inlineMin);
                    childMin -= ti;
                }

                inlineMin = childMin;

                if (hasBreakableEnd) {
                    updatePreferredWidth(minLogicalWidth, inlineMin);
                    inlineMin = 0;
                    shouldBreakLineAfterText = false;
                } else {
                    updatePreferredWidth(minLogicalWidth, inlineMin);
                    inlineMin = lastLineMinWidth;
                    shouldBreakLineAfterText = true;
                }
            }

            if (hasBreak) {
                inlineMax += firstLineMaxWidth;
                updatePreferredWidth(maxLogicalWidth, inlineMax);
                updatePreferredWidth(maxLogicalWidth, childMax);
                inlineMax = lastLineMaxWidth;
                addedTextIndent = true;
            } else {
                inlineMax += std::max<float>(0, childMax);
            }
        }

        if (!child->isText() && child->isRenderInline())
            isPrevChildInlineFlow = true;
        else
            isPrevChildInlineFlow = false;

        oldAutoWrap = autoWrap;
    }

    if (styleToUse->collapseWhiteSpace())
        stripTrailingSpace(inlineMax, inlineMin, trailingSpaceChild);

    updatePreferredWidth(minLogicalWidth, inlineMin);
    updatePreferredWidth(maxLogicalWidth, inlineMax);

    maxLogicalWidth = std::max(minLogicalWidth, maxLogicalWidth);
}

int RenderParagraph::firstLineBoxBaseline(FontBaselineOrAuto baselineType) const
{
  if (!firstLineBox())
    return -1;
  FontBaseline baseline;
  if (baselineType.m_auto)
    baseline = firstRootBox()->baselineType();
  else
    baseline = baselineType.m_baseline;
  return firstLineBox()->logicalTop() + style(true)->fontMetrics().ascent(baseline);
}

int RenderParagraph::lastLineBoxBaseline(LineDirectionMode lineDirection) const
{
    if (!firstLineBox() && hasLineIfEmpty()) {
        const FontMetrics& fontMetrics = firstLineStyle()->fontMetrics();
        return fontMetrics.ascent()
             + (lineHeight(true, lineDirection, PositionOfInteriorLineBoxes) - fontMetrics.height()) / 2
             + (lineDirection == HorizontalLine ? borderTop() + paddingTop() : borderRight() + paddingRight());
    }
    if (lastLineBox())
        return lastLineBox()->logicalTop() + style(lastLineBox() == firstLineBox())->fontMetrics().ascent(lastRootBox()->baselineType());
    return -1;
}

void RenderParagraph::layout()
{
    ASSERT(needsLayout());
    ASSERT(isInlineBlock() || !isInline());

    if (simplifiedLayout())
        return;

    SubtreeLayoutScope layoutScope(*this);

    LayoutUnit oldLeft = logicalLeft();
    bool logicalWidthChanged = updateLogicalWidthAndColumnWidth();
    bool relayoutChildren = logicalWidthChanged;

    LayoutUnit beforeEdge = borderBefore() + paddingBefore();
    LayoutUnit afterEdge = borderAfter() + paddingAfter();
    LayoutUnit previousHeight = logicalHeight();
    setLogicalHeight(beforeEdge);

    layoutChildren(relayoutChildren, layoutScope, beforeEdge, afterEdge);

    LayoutUnit oldClientAfterEdge = clientLogicalBottom();

    updateLogicalHeight();

    if (previousHeight != logicalHeight())
        relayoutChildren = true;

    layoutPositionedObjects(relayoutChildren, oldLeft != logicalLeft() ? ForcedLayoutAfterContainingBlockMoved : DefaultLayout);

    // Add overflow from children (unless we're multi-column, since in that case all our child overflow is clipped anyway).
    computeOverflow(oldClientAfterEdge);

    updateLayerTransformAfterLayout();

    clearNeedsLayout();
}

void RenderParagraph::layoutChildren(bool relayoutChildren, SubtreeLayoutScope& layoutScope, LayoutUnit beforeEdge, LayoutUnit afterEdge)
{
    // Figure out if we should clear out our line boxes.
    // FIXME: Handle resize eventually!
    bool isFullLayout = !firstLineBox() || selfNeedsLayout() || relayoutChildren;
    LineLayoutState layoutState(isFullLayout);

    if (isFullLayout)
        lineBoxes()->deleteLineBoxes();

    if (firstChild()) {
        // In full layout mode, clear the line boxes of children upfront. Otherwise,
        // siblings can run into stale root lineboxes during layout. Then layout
        // the replaced elements later. In partial layout mode, line boxes are not
        // deleted and only dirtied. In that case, we can layout the replaced
        // elements at the same time.
        Vector<RenderBox*> replacedChildren;
        for (InlineWalker walker(this); !walker.atEnd(); walker.advance()) {
            RenderObject* o = walker.current();

            if (!layoutState.hasInlineChild() && o->isInline())
                layoutState.setHasInlineChild(true);

            if (o->isReplaced() || o->isOutOfFlowPositioned()) {
                RenderBox* box = toRenderBox(o);

                updateBlockChildDirtyBitsBeforeLayout(relayoutChildren, box);

                if (o->isOutOfFlowPositioned()) {
                    o->containingBlock()->insertPositionedObject(box);
                } else if (isFullLayout || o->needsLayout()) {
                    // Replaced element.
                    box->dirtyLineBoxes(isFullLayout);
                    if (isFullLayout)
                        replacedChildren.append(box);
                    else
                        o->layoutIfNeeded();
                }
            } else if (o->isText() || (o->isRenderInline() && !walker.atEndOfInline())) {
                if (!o->isText())
                    toRenderInline(o)->updateAlwaysCreateLineBoxes(layoutState.isFullLayout());
                if (layoutState.isFullLayout() || o->selfNeedsLayout())
                    dirtyLineBoxesForRenderer(o, layoutState.isFullLayout());
                o->clearNeedsLayout();
            }
        }

        for (size_t i = 0; i < replacedChildren.size(); i++)
            replacedChildren[i]->layoutIfNeeded();

        layoutRunsAndFloats(layoutState);
    }

    // Expand the last line to accommodate Ruby and emphasis marks.
    int lastLineAnnotationsAdjustment = 0;
    if (lastRootBox()) {
        LayoutUnit lowestAllowedPosition = std::max(lastRootBox()->lineBottom(), logicalHeight() + paddingAfter());
        lastLineAnnotationsAdjustment = lastRootBox()->computeUnderAnnotationAdjustment(lowestAllowedPosition);
    }

    // Now add in the bottom border/padding.
    setLogicalHeight(logicalHeight() + lastLineAnnotationsAdjustment + afterEdge);

    if (!firstLineBox() && hasLineIfEmpty())
        setLogicalHeight(logicalHeight() + lineHeight(true, HorizontalLine, PositionOfInteriorLineBoxes));
}

RootInlineBox* RenderParagraph::determineStartPosition(LineLayoutState& layoutState, InlineBidiResolver& resolver)
{
    RootInlineBox* curr = 0;
    RootInlineBox* last = 0;

    if (layoutState.isFullLayout()) {
        // If we encountered a new float and have inline children, mark ourself to force us to issue paint invalidations.
        if (layoutState.hasInlineChild() && !selfNeedsLayout()) {
            setNeedsLayout(MarkOnlyThis);
        }

        // FIXME: This should just call deleteLineBoxTree, but that causes
        // crashes for fast/repaint tests.
        curr = firstRootBox();
        while (curr) {
            // Note: This uses nextRootBox() insted of nextLineBox() like deleteLineBoxTree does.
            RootInlineBox* next = curr->nextRootBox();
            curr->deleteLine();
            curr = next;
        }
        ASSERT(!firstLineBox() && !lastLineBox());
    } else {
        if (curr) {
            // We have a dirty line.
            if (RootInlineBox* prevRootBox = curr->prevRootBox()) {
                // We have a previous line.
                if (!prevRootBox->endsWithBreak() || !prevRootBox->lineBreakObj() || (prevRootBox->lineBreakObj()->isText() && prevRootBox->lineBreakPos() >= toRenderText(prevRootBox->lineBreakObj())->textLength()))
                    // The previous line didn't break cleanly or broke at a newline
                    // that has been deleted, so treat it as dirty too.
                    curr = prevRootBox;
            }
        } else {
            // No dirty lines were found.
            // If the last line didn't break cleanly, treat it as dirty.
            if (lastRootBox() && !lastRootBox()->endsWithBreak())
                curr = lastRootBox();
        }

        // If we have no dirty lines, then last is just the last root box.
        last = curr ? curr->prevRootBox() : lastRootBox();
    }

    layoutState.lineInfo().setFirstLine(!last);
    layoutState.lineInfo().setPreviousLineBrokeCleanly(!last || last->endsWithBreak());

    if (last) {
        setLogicalHeight(last->lineBottomWithLeading());
        InlineIterator iter = InlineIterator(this, last->lineBreakObj(), last->lineBreakPos());
        resolver.setPosition(iter, numberOfIsolateAncestors(iter));
        resolver.setStatus(last->lineBreakBidiStatus());
    } else {
        TextDirection direction = style()->direction();
        if (style()->unicodeBidi() == Plaintext)
            direction = determinePlaintextDirectionality(this);
        resolver.setStatus(BidiStatus(direction, isOverride(style()->unicodeBidi())));
        InlineIterator iter = InlineIterator(this, bidiFirstSkippingEmptyInlines(this, resolver.runs(), &resolver), 0);
        resolver.setPosition(iter, numberOfIsolateAncestors(iter));
    }
    return curr;
}

void RenderParagraph::determineEndPosition(LineLayoutState& layoutState, RootInlineBox* startLine, InlineIterator& cleanLineStart, BidiStatus& cleanLineBidiStatus)
{
    ASSERT(!layoutState.endLine());
    RootInlineBox* last = 0;
    for (RootInlineBox* curr = startLine->nextRootBox(); curr; curr = curr->nextRootBox()) {
        if (curr->isDirty())
            last = 0;
        else if (!last)
            last = curr;
    }

    if (!last)
        return;

    // At this point, |last| is the first line in a run of clean lines that ends with the last line
    // in the block.

    RootInlineBox* prev = last->prevRootBox();
    cleanLineStart = InlineIterator(this, prev->lineBreakObj(), prev->lineBreakPos());
    cleanLineBidiStatus = prev->lineBreakBidiStatus();
    layoutState.setEndLineLogicalTop(prev->lineBottomWithLeading());

    for (RootInlineBox* line = last; line; line = line->nextRootBox())
        line->extractLine(); // Disconnect all line boxes from their render objects while preserving
                             // their connections to one another.

    layoutState.setEndLine(last);
}

bool RenderParagraph::checkPaginationAndFloatsAtEndLine(LineLayoutState& layoutState)
{
    // FIXME(sky): Remove this.
    return true;
}

bool RenderParagraph::matchedEndLine(LineLayoutState& layoutState, const InlineBidiResolver& resolver, const InlineIterator& endLineStart, const BidiStatus& endLineStatus)
{
    if (resolver.position() == endLineStart) {
        if (resolver.status() != endLineStatus)
            return false;
        return checkPaginationAndFloatsAtEndLine(layoutState);
    }

    // The first clean line doesn't match, but we can check a handful of following lines to try
    // to match back up.
    static int numLines = 8; // The # of lines we're willing to match against.
    RootInlineBox* originalEndLine = layoutState.endLine();
    RootInlineBox* line = originalEndLine;
    for (int i = 0; i < numLines && line; i++, line = line->nextRootBox()) {
        if (line->lineBreakObj() == resolver.position().object() && line->lineBreakPos() == resolver.position().offset()) {
            // We have a match.
            if (line->lineBreakBidiStatus() != resolver.status())
                return false; // ...but the bidi state doesn't match.

            bool matched = false;
            RootInlineBox* result = line->nextRootBox();
            layoutState.setEndLine(result);
            if (result) {
                layoutState.setEndLineLogicalTop(line->lineBottomWithLeading());
                matched = checkPaginationAndFloatsAtEndLine(layoutState);
            }

            // Now delete the lines that we failed to sync.
            deleteLineRange(layoutState, originalEndLine, result);
            return matched;
        }
    }

    return false;
}

} // namespace blink