[css-grid] Refactor GridSpan to avoid pointers

third_party/WebKit/Source/core/layout/LayoutGrid.cpp

 /*
  * Copyright (C) 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 191 matching lines @@
         ASSERT(!m_grid.isEmpty());
         ASSERT(fixedTrackSpan >= 1 && varyingTrackSpan >= 1);
 
         size_t rowSpan = (m_direction == ForColumns) ? varyingTrackSpan : fixedTrackSpan;
         size_t columnSpan = (m_direction == ForColumns) ? fixedTrackSpan : varyingTrackSpan;
 
         size_t& varyingTrackIndex = (m_direction == ForColumns) ? m_rowIndex : m_columnIndex;
         const size_t endOfVaryingTrackIndex = (m_direction == ForColumns) ? m_grid.size() : m_grid[0].size();
         for (; varyingTrackIndex < endOfVaryingTrackIndex; ++varyingTrackIndex) {
             if (checkEmptyCells(rowSpan, columnSpan)) {
-                OwnPtr<GridCoordinate> result = adoptPtr(new GridCoordinate(GridSpan(m_rowIndex, m_rowIndex + rowSpan), GridSpan(m_columnIndex, m_columnIndex + columnSpan)));
+                OwnPtr<GridCoordinate> result = adoptPtr(new GridCoordinate(GridSpan::definiteGridSpan(m_rowIndex, m_rowIndex + rowSpan), GridSpan::definiteGridSpan(m_columnIndex, m_columnIndex + columnSpan)));
                 // Advance the iterator to avoid an infinite loop where we would return the same grid area over and over.
                 ++varyingTrackIndex;
                 return result.release();
             }
         }
         return nullptr;
     }
 
 private:
     const GridRepresentation& m_grid;
@@ skipping 306 matching lines @@
         for (auto& track : tracks)
             track.setBaseSize(track.growthLimit());
     }
 
     if (flexibleSizedTracksIndex.isEmpty())
         return;
 
     // 4. Grow all Grid tracks having a fraction as the MaxTrackSizingFunction.
     double flexFraction = 0;
     if (hasDefiniteFreeSpace) {
-        flexFraction = findFlexFactorUnitSize(tracks, GridSpan(0, tracks.size()), direction, initialFreeSpace);
+        flexFraction = findFlexFactorUnitSize(tracks, GridSpan::definiteGridSpan(0, tracks.size()), direction, initialFreeSpace);
     } else {
         for (const auto& trackIndex : flexibleSizedTracksIndex)
             flexFraction = std::max(flexFraction, normalizedFlexFraction(tracks[trackIndex], gridTrackSize(direction, trackIndex).maxTrackBreadth().flex()));
 
         for (size_t i = 0; i < flexibleSizedTracksIndex.size(); ++i) {
             GridIterator iterator(m_grid, direction, flexibleSizedTracksIndex[i]);
             while (LayoutBox* gridItem = iterator.nextGridItem()) {
                 const GridSpan span = cachedGridSpan(*gridItem, direction);
 
                 // Do not include already processed items.
-                if (i > 0 && span.resolvedInitialPosition.toInt() <= flexibleSizedTracksIndex[i - 1])
+                if (i > 0 && span.resolvedInitialPosition().toInt() <= flexibleSizedTracksIndex[i - 1])
                     continue;
 
                 flexFraction = std::max(flexFraction, findFlexFactorUnitSize(tracks, span, direction, maxContentForChild(*gridItem, direction, sizingData.columnTracks)));
             }
         }
     }
 
     for (const auto& trackIndex : flexibleSizedTracksIndex) {
         GridTrackSize trackSize = gridTrackSize(direction, trackIndex);
 
@@ skipping 266 matching lines @@
 
     for (const auto& trackIndex : sizingData.contentSizedTracksIndex) {
         GridTrack& track = (direction == ForColumns) ? sizingData.columnTracks[trackIndex] : sizingData.rowTracks[trackIndex];
         if (track.growthLimitIsInfinite())
             track.setGrowthLimit(track.baseSize());
     }
 }
 
 void LayoutGrid::resolveContentBasedTrackSizingFunctionsForNonSpanningItems(GridTrackSizingDirection direction, const GridSpan& span, LayoutBox& gridItem, GridTrack& track, Vector<GridTrack>& columnTracks)
 {
-    const GridResolvedPosition trackPosition = span.resolvedInitialPosition;
+    const GridResolvedPosition trackPosition = span.resolvedInitialPosition();
     GridTrackSize trackSize = gridTrackSize(direction, trackPosition.toInt());
 
     if (trackSize.hasMinContentMinTrackBreadth())
         track.setBaseSize(std::max(track.baseSize(), minContentForChild(gridItem, direction, columnTracks)));
     else if (trackSize.hasMaxContentMinTrackBreadth())
         track.setBaseSize(std::max(track.baseSize(), maxContentForChild(gridItem, direction, columnTracks)));
     else if (trackSize.hasAutoMinTrackBreadth())
         track.setBaseSize(std::max(track.baseSize(), minSizeForChild(gridItem, direction, columnTracks)));
 
     if (trackSize.hasMinContentMaxTrackBreadth())
@@ skipping 250 matching lines @@
     }
 
     if (maximumColumnSize > gridColumnCount()) {
         for (size_t row = 0; row < gridRowCount(); ++row)
             m_grid[row].grow(maximumColumnSize);
     }
 }
 
 void LayoutGrid::insertItemIntoGrid(LayoutBox& child, const GridCoordinate& coordinate)
 {
-    ensureGridSize(coordinate.rows.resolvedFinalPosition.toInt(), coordinate.columns.resolvedFinalPosition.toInt());
+    ensureGridSize(coordinate.rows.resolvedFinalPosition().toInt(), coordinate.columns.resolvedFinalPosition().toInt());
 
     for (GridSpan::iterator row = coordinate.rows.begin(); row != coordinate.rows.end(); ++row) {
         for (GridSpan::iterator column = coordinate.columns.begin(); column != coordinate.columns.end(); ++column)
             m_grid[row.toInt()][column.toInt()].append(&child);
     }
 
     RELEASE_ASSERT(!m_gridItemCoordinate.contains(&child));
     m_gridItemCoordinate.set(&child, coordinate);
 }
 
 void LayoutGrid::placeItemsOnGrid()
 {
     if (!m_gridIsDirty)
         return;
 
     ASSERT(m_gridItemCoordinate.isEmpty());
 
     populateExplicitGridAndOrderIterator();
 
     // We clear the dirty bit here as the grid sizes have been updated.
     m_gridIsDirty = false;
 
     Vector<LayoutBox*> autoMajorAxisAutoGridItems;
     Vector<LayoutBox*> specifiedMajorAxisAutoGridItems;
     for (LayoutBox* child = m_orderIterator.first(); child; child = m_orderIterator.next()) {
         if (child->isOutOfFlowPositioned())
             continue;
 
-        OwnPtr<GridSpan> rowPositions = GridResolvedPosition::resolveGridPositionsFromStyle(*style(), *child, ForRows);
-        OwnPtr<GridSpan> columnPositions = GridResolvedPosition::resolveGridPositionsFromStyle(*style(), *child, ForColumns);
-        if (!rowPositions || !columnPositions) {
-            GridSpan* majorAxisPositions = (autoPlacementMajorAxisDirection() == ForColumns) ? columnPositions.get() : rowPositions.get();
-            if (!majorAxisPositions)
+        GridSpan rowPositions = GridResolvedPosition::resolveGridPositionsFromStyle(*style(), *child, ForRows);
+        GridSpan columnPositions = GridResolvedPosition::resolveGridPositionsFromStyle(*style(), *child, ForColumns);
+        if (!rowPositions.isDefinite() || !columnPositions.isDefinite()) {
+            GridSpan majorAxisPositions = (autoPlacementMajorAxisDirection() == ForColumns) ? columnPositions : rowPositions;
+            if (!majorAxisPositions.isDefinite())
                 autoMajorAxisAutoGridItems.append(child);
             else
                 specifiedMajorAxisAutoGridItems.append(child);
             continue;
         }
-        insertItemIntoGrid(*child, GridCoordinate(*rowPositions, *columnPositions));
+        insertItemIntoGrid(*child, GridCoordinate(rowPositions, columnPositions));
     }
 
     ASSERT(gridRowCount() >= GridResolvedPosition::explicitGridRowCount(*style()));
     ASSERT(gridColumnCount() >= GridResolvedPosition::explicitGridColumnCount(*style()));
 
     placeSpecifiedMajorAxisItemsOnGrid(specifiedMajorAxisAutoGridItems);
     placeAutoMajorAxisItemsOnGrid(autoMajorAxisAutoGridItems);
 
     m_grid.shrinkToFit();
 }
 
 void LayoutGrid::populateExplicitGridAndOrderIterator()
 {
     OrderIteratorPopulator populator(m_orderIterator);
 
     size_t maximumRowIndex = std::max<size_t>(1, GridResolvedPosition::explicitGridRowCount(*style()));
     size_t maximumColumnIndex = std::max<size_t>(1, GridResolvedPosition::explicitGridColumnCount(*style()));
 
     ASSERT(m_gridItemsIndexesMap.isEmpty());
     size_t childIndex = 0;
     for (LayoutBox* child = firstChildBox(); child; child = child->nextInFlowSiblingBox()) {
         if (child->isOutOfFlowPositioned())
             continue;
 
         populator.collectChild(child);
         m_gridItemsIndexesMap.set(child, childIndex++);
 
         // This function bypasses the cache (cachedGridCoordinate()) as it is used to build it.
-        OwnPtr<GridSpan> rowPositions = GridResolvedPosition::resolveGridPositionsFromStyle(*style(), *child, ForRows);
-        OwnPtr<GridSpan> columnPositions = GridResolvedPosition::resolveGridPositionsFromStyle(*style(), *child, ForColumns);
+        GridSpan rowPositions = GridResolvedPosition::resolveGridPositionsFromStyle(*style(), *child, ForRows);
+        GridSpan columnPositions = GridResolvedPosition::resolveGridPositionsFromStyle(*style(), *child, ForColumns);
 
         // |positions| is 0 if we need to run the auto-placement algorithm.
-        if (rowPositions) {
-            maximumRowIndex = std::max<size_t>(maximumRowIndex, rowPositions->resolvedFinalPosition.toInt());
+        if (rowPositions.isDefinite()) {
+            maximumRowIndex = std::max<size_t>(maximumRowIndex, rowPositions.resolvedFinalPosition().toInt());
         } else {
             // Grow the grid for items with a definite row span, getting the largest such span.
             GridSpan positions = GridResolvedPosition::resolveGridPositionsFromAutoPlacementPosition(*style(), *child, ForRows, GridResolvedPosition(0));
-            maximumRowIndex = std::max<size_t>(maximumRowIndex, positions.resolvedFinalPosition.toInt());
+            maximumRowIndex = std::max<size_t>(maximumRowIndex, positions.resolvedFinalPosition().toInt());
         }
 
-        if (columnPositions) {
-            maximumColumnIndex = std::max<size_t>(maximumColumnIndex, columnPositions->resolvedFinalPosition.toInt());
+        if (columnPositions.isDefinite()) {
+            maximumColumnIndex = std::max<size_t>(maximumColumnIndex, columnPositions.resolvedFinalPosition().toInt());
         } else {
             // Grow the grid for items with a definite column span, getting the largest such span.
             GridSpan positions = GridResolvedPosition::resolveGridPositionsFromAutoPlacementPosition(*style(), *child, ForColumns, GridResolvedPosition(0));
-            maximumColumnIndex = std::max<size_t>(maximumColumnIndex, positions.resolvedFinalPosition.toInt());
+            maximumColumnIndex = std::max<size_t>(maximumColumnIndex, positions.resolvedFinalPosition().toInt());
         }
     }
 
     m_grid.grow(maximumRowIndex);
     for (auto& column : m_grid)
         column.grow(maximumColumnIndex);
 }
 
 PassOwnPtr<GridCoordinate> LayoutGrid::createEmptyGridAreaAtSpecifiedPositionsOutsideGrid(const LayoutBox& gridItem, GridTrackSizingDirection specifiedDirection, const GridSpan& specifiedPositions) const
 {
     GridTrackSizingDirection crossDirection = specifiedDirection == ForColumns ? ForRows : ForColumns;
     const size_t endOfCrossDirection = crossDirection == ForColumns ? gridColumnCount() : gridRowCount();
     GridSpan crossDirectionPositions = GridResolvedPosition::resolveGridPositionsFromAutoPlacementPosition(*style(), gridItem, crossDirection, GridResolvedPosition(endOfCrossDirection));
     return adoptPtr(new GridCoordinate(specifiedDirection == ForColumns ? crossDirectionPositions : specifiedPositions, specifiedDirection == ForColumns ? specifiedPositions : crossDirectionPositions));
 }
 
 void LayoutGrid::placeSpecifiedMajorAxisItemsOnGrid(const Vector<LayoutBox*>& autoGridItems)
 {
     bool isForColumns = autoPlacementMajorAxisDirection() == ForColumns;
     bool isGridAutoFlowDense = style()->isGridAutoFlowAlgorithmDense();
 
     // Mapping between the major axis tracks (rows or columns) and the last auto-placed item's position inserted on
     // that track. This is needed to implement "sparse" packing for items locked to a given track.
     // See http://dev.w3.org/csswg/css-grid/#auto-placement-algo
     HashMap<unsigned, unsigned, DefaultHash<unsigned>::Hash, WTF::UnsignedWithZeroKeyHashTraits<unsigned>> minorAxisCursors;
 
     for (const auto& autoGridItem : autoGridItems) {
-        OwnPtr<GridSpan> majorAxisPositions = GridResolvedPosition::resolveGridPositionsFromStyle(*style(), *autoGridItem, autoPlacementMajorAxisDirection());
+        GridSpan majorAxisPositions = GridResolvedPosition::resolveGridPositionsFromStyle(*style(), *autoGridItem, autoPlacementMajorAxisDirection());
         GridSpan minorAxisPositions = GridResolvedPosition::resolveGridPositionsFromAutoPlacementPosition(*style(), *autoGridItem, autoPlacementMinorAxisDirection(), GridResolvedPosition(0));
-        unsigned majorAxisInitialPosition = majorAxisPositions->resolvedInitialPosition.toInt();
+        unsigned majorAxisInitialPosition = majorAxisPositions.resolvedInitialPosition().toInt();
 
-        GridIterator iterator(m_grid, autoPlacementMajorAxisDirection(), majorAxisPositions->resolvedInitialPosition.toInt(), isGridAutoFlowDense ? 0 : minorAxisCursors.get(majorAxisInitialPosition));
-        OwnPtr<GridCoordinate> emptyGridArea = iterator.nextEmptyGridArea(majorAxisPositions->integerSpan(), minorAxisPositions.integerSpan());
+        GridIterator iterator(m_grid, autoPlacementMajorAxisDirection(), majorAxisPositions.resolvedInitialPosition().toInt(), isGridAutoFlowDense ? 0 : minorAxisCursors.get(majorAxisInitialPosition));
+        OwnPtr<GridCoordinate> emptyGridArea = iterator.nextEmptyGridArea(majorAxisPositions.integerSpan(), minorAxisPositions.integerSpan());
         if (!emptyGridArea)
-            emptyGridArea = createEmptyGridAreaAtSpecifiedPositionsOutsideGrid(*autoGridItem, autoPlacementMajorAxisDirection(), *majorAxisPositions);
+            emptyGridArea = createEmptyGridAreaAtSpecifiedPositionsOutsideGrid(*autoGridItem, autoPlacementMajorAxisDirection(), majorAxisPositions);
         insertItemIntoGrid(*autoGridItem, *emptyGridArea);
 
         if (!isGridAutoFlowDense)
-            minorAxisCursors.set(majorAxisInitialPosition, isForColumns ? emptyGridArea->rows.resolvedInitialPosition.toInt() : emptyGridArea->columns.resolvedInitialPosition.toInt());
+            minorAxisCursors.set(majorAxisInitialPosition, isForColumns ? emptyGridArea->rows.resolvedInitialPosition().toInt() : emptyGridArea->columns.resolvedInitialPosition().toInt());
     }
 }
 
 void LayoutGrid::placeAutoMajorAxisItemsOnGrid(const Vector<LayoutBox*>& autoGridItems)
 {
     std::pair<size_t, size_t> autoPlacementCursor = std::make_pair(0, 0);
     bool isGridAutoFlowDense = style()->isGridAutoFlowAlgorithmDense();
 
     for (const auto& autoGridItem : autoGridItems) {
         placeAutoMajorAxisItemOnGrid(*autoGridItem, autoPlacementCursor);
 
         // If grid-auto-flow is dense, reset auto-placement cursor.
         if (isGridAutoFlowDense) {
             autoPlacementCursor.first = 0;
             autoPlacementCursor.second = 0;
         }
     }
 }
 
 void LayoutGrid::placeAutoMajorAxisItemOnGrid(LayoutBox& gridItem, std::pair<size_t, size_t>& autoPlacementCursor)
 {
-    OwnPtr<GridSpan> minorAxisPositions = GridResolvedPosition::resolveGridPositionsFromStyle(*style(), gridItem, autoPlacementMinorAxisDirection());
-    ASSERT(!GridResolvedPosition::resolveGridPositionsFromStyle(*style(), gridItem, autoPlacementMajorAxisDirection()));
+    GridSpan minorAxisPositions = GridResolvedPosition::resolveGridPositionsFromStyle(*style(), gridItem, autoPlacementMinorAxisDirection());
+    ASSERT(!GridResolvedPosition::resolveGridPositionsFromStyle(*style(), gridItem, autoPlacementMajorAxisDirection()).isDefinite());
     GridSpan majorAxisPositions = GridResolvedPosition::resolveGridPositionsFromAutoPlacementPosition(*style(), gridItem, autoPlacementMajorAxisDirection(), GridResolvedPosition(0));
 
     const size_t endOfMajorAxis = (autoPlacementMajorAxisDirection() == ForColumns) ? gridColumnCount() : gridRowCount();
     size_t majorAxisAutoPlacementCursor = autoPlacementMajorAxisDirection() == ForColumns ? autoPlacementCursor.second : autoPlacementCursor.first;
     size_t minorAxisAutoPlacementCursor = autoPlacementMajorAxisDirection() == ForColumns ? autoPlacementCursor.first : autoPlacementCursor.second;
 
     OwnPtr<GridCoordinate> emptyGridArea;
-    if (minorAxisPositions) {
+    if (minorAxisPositions.isDefinite()) {
         // Move to the next track in major axis if initial position in minor axis is before auto-placement cursor.
-        if (minorAxisPositions->resolvedInitialPosition.toInt() < minorAxisAutoPlacementCursor)
+        if (minorAxisPositions.resolvedInitialPosition().toInt() < minorAxisAutoPlacementCursor)
             majorAxisAutoPlacementCursor++;
 
         if (majorAxisAutoPlacementCursor < endOfMajorAxis) {
-            GridIterator iterator(m_grid, autoPlacementMinorAxisDirection(), minorAxisPositions->resolvedInitialPosition.toInt(), majorAxisAutoPlacementCursor);
-            emptyGridArea = iterator.nextEmptyGridArea(minorAxisPositions->integerSpan(), majorAxisPositions.integerSpan());
+            GridIterator iterator(m_grid, autoPlacementMinorAxisDirection(), minorAxisPositions.resolvedInitialPosition().toInt(), majorAxisAutoPlacementCursor);
+            emptyGridArea = iterator.nextEmptyGridArea(minorAxisPositions.integerSpan(), majorAxisPositions.integerSpan());
         }
 
         if (!emptyGridArea)
-            emptyGridArea = createEmptyGridAreaAtSpecifiedPositionsOutsideGrid(gridItem, autoPlacementMinorAxisDirection(), *minorAxisPositions);
+            emptyGridArea = createEmptyGridAreaAtSpecifiedPositionsOutsideGrid(gridItem, autoPlacementMinorAxisDirection(), minorAxisPositions);
     } else {
         GridSpan minorAxisPositions = GridResolvedPosition::resolveGridPositionsFromAutoPlacementPosition(*style(), gridItem, autoPlacementMinorAxisDirection(), GridResolvedPosition(0));
 
         for (size_t majorAxisIndex = majorAxisAutoPlacementCursor; majorAxisIndex < endOfMajorAxis; ++majorAxisIndex) {
             GridIterator iterator(m_grid, autoPlacementMajorAxisDirection(), majorAxisIndex, minorAxisAutoPlacementCursor);
             emptyGridArea = iterator.nextEmptyGridArea(majorAxisPositions.integerSpan(), minorAxisPositions.integerSpan());
 
             if (emptyGridArea) {
                 // Check that it fits in the minor axis direction, as we shouldn't grow in that direction here (it was already managed in populateExplicitGridAndOrderIterator()).
-                GridResolvedPosition minorAxisFinalPositionIndex = autoPlacementMinorAxisDirection() == ForColumns ? emptyGridArea->columns.resolvedFinalPosition : emptyGridArea->rows.resolvedFinalPosition;
+                GridResolvedPosition minorAxisFinalPositionIndex = autoPlacementMinorAxisDirection() == ForColumns ? emptyGridArea->columns.resolvedFinalPosition() : emptyGridArea->rows.resolvedFinalPosition();
                 const size_t endOfMinorAxis = autoPlacementMinorAxisDirection() == ForColumns ? gridColumnCount() : gridRowCount();
                 if (minorAxisFinalPositionIndex.toInt() <= endOfMinorAxis)
                     break;
 
                 // Discard empty grid area as it does not fit in the minor axis direction.
                 // We don't need to create a new empty grid area yet as we might find a valid one in the next iteration.
                 emptyGridArea = nullptr;
             }
 
             // As we're moving to the next track in the major axis we should reset the auto-placement cursor in the minor axis.
             minorAxisAutoPlacementCursor = 0;
         }
 
         if (!emptyGridArea)
             emptyGridArea = createEmptyGridAreaAtSpecifiedPositionsOutsideGrid(gridItem, autoPlacementMinorAxisDirection(), minorAxisPositions);
     }
 
     insertItemIntoGrid(gridItem, *emptyGridArea);
     // Move auto-placement cursor to the new position.
-    autoPlacementCursor.first = emptyGridArea->rows.resolvedInitialPosition.toInt();
-    autoPlacementCursor.second = emptyGridArea->columns.resolvedInitialPosition.toInt();
+    autoPlacementCursor.first = emptyGridArea->rows.resolvedInitialPosition().toInt();
+    autoPlacementCursor.second = emptyGridArea->columns.resolvedInitialPosition().toInt();
 }
 
 GridTrackSizingDirection LayoutGrid::autoPlacementMajorAxisDirection() const
 {
     return style()->isGridAutoFlowDirectionColumn() ? ForColumns : ForRows;
 }
 
 GridTrackSizingDirection LayoutGrid::autoPlacementMinorAxisDirection() const
 {
     return style()->isGridAutoFlowDirectionColumn() ? ForRows : ForColumns;
@@ skipping 82 matching lines @@
         applyStretchAlignmentToChildIfNeeded(*child);
 
         child->layoutIfNeeded();
 
         // We need pending layouts to be done in order to compute auto-margins properly.
         updateAutoMarginsInColumnAxisIfNeeded(*child);
         updateAutoMarginsInRowAxisIfNeeded(*child);
 
 #if ENABLE(ASSERT)
         const GridCoordinate& coordinate = cachedGridCoordinate(*child);
-        ASSERT(coordinate.columns.resolvedInitialPosition.toInt() < sizingData.columnTracks.size());
-        ASSERT(coordinate.rows.resolvedInitialPosition.toInt() < sizingData.rowTracks.size());
+        ASSERT(coordinate.columns.resolvedInitialPosition().toInt() < sizingData.columnTracks.size());
+        ASSERT(coordinate.rows.resolvedInitialPosition().toInt() < sizingData.rowTracks.size());
 #endif
         child->setLogicalLocation(findChildLogicalPosition(*child, sizingData));
 
         // Keep track of children overflowing their grid area as we might need to paint them even if the grid-area is
         // not visible
         if (child->logicalHeight() > overrideContainingBlockContentLogicalHeight
             || child->logicalWidth() > overrideContainingBlockContentLogicalWidth)
             m_gridItemsOverflowingGridArea.append(child);
     }
 }
@@ skipping 35 matching lines @@
         child->setExtraBlockOffset(rowOffset);
     }
 
     LayoutBlock::layoutPositionedObjects(relayoutChildren, info);
 }
 
 void LayoutGrid::offsetAndBreadthForPositionedChild(const LayoutBox& child, GridTrackSizingDirection direction, LayoutUnit& offset, LayoutUnit& breadth)
 {
     ASSERT(child.isHorizontalWritingMode() == isHorizontalWritingMode());
 
-    OwnPtr<GridSpan> positions = GridResolvedPosition::resolveGridPositionsFromStyle(*style(), child, direction);
-    if (!positions) {
+    GridSpan positions = GridResolvedPosition::resolveGridPositionsFromStyle(*style(), child, direction);
+    if (!positions.isDefinite()) {
         offset = LayoutUnit();
         breadth = (direction == ForColumns) ? clientLogicalWidth() : clientLogicalHeight();
         return;
     }
 
     GridPosition startPosition = (direction == ForColumns) ? child.style()->gridColumnStart() : child.style()->gridRowStart();
     GridPosition endPosition = (direction == ForColumns) ? child.style()->gridColumnEnd() : child.style()->gridRowEnd();
     size_t lastTrackIndex = (direction == ForColumns ? gridColumnCount() : gridRowCount()) - 1;
 
     bool startIsAuto = startPosition.isAuto()
         || (startPosition.isNamedGridArea() && !GridResolvedPosition::isValidNamedLineOrArea(startPosition.namedGridLine(), styleRef(), GridResolvedPosition::initialPositionSide(direction)))
-        || (positions->resolvedInitialPosition.toInt() > lastTrackIndex);
+        || (positions.resolvedInitialPosition().toInt() > lastTrackIndex);
     bool endIsAuto = endPosition.isAuto()
         || (endPosition.isNamedGridArea() && !GridResolvedPosition::isValidNamedLineOrArea(endPosition.namedGridLine(), styleRef(), GridResolvedPosition::finalPositionSide(direction)))
-        || (positions->resolvedFinalPosition.prev().toInt() > lastTrackIndex);
+        || (positions.resolvedFinalPosition().prev().toInt() > lastTrackIndex);
 
     GridResolvedPosition firstPosition = GridResolvedPosition(0);
-    GridResolvedPosition initialPosition = startIsAuto ? firstPosition : positions->resolvedInitialPosition;
+    GridResolvedPosition initialPosition = startIsAuto ? firstPosition : positions.resolvedInitialPosition();
     GridResolvedPosition lastPosition = GridResolvedPosition(lastTrackIndex);
-    GridResolvedPosition finalPosition = endIsAuto ? lastPosition : positions->resolvedFinalPosition.prev();
+    GridResolvedPosition finalPosition = endIsAuto ? lastPosition : positions.resolvedFinalPosition().prev();
 
     // Positioned children do not grow the grid, so we need to clamp the positions to avoid ending up outside of it.
     initialPosition = std::min<GridResolvedPosition>(initialPosition, lastPosition);
     finalPosition = std::min<GridResolvedPosition>(finalPosition, lastPosition);
 
     LayoutUnit start = startIsAuto ? LayoutUnit() : (direction == ForColumns) ?  m_columnPositions[initialPosition.toInt()] : m_rowPositions[initialPosition.toInt()];
     LayoutUnit end = endIsAuto ? (direction == ForColumns) ? logicalWidth() : logicalHeight() : (direction == ForColumns) ?  m_columnPositions[finalPosition.next().toInt()] : m_rowPositions[finalPosition.next().toInt()];
 
     breadth = end - start;
 
@@ skipping 43 matching lines @@
     return gridAreaBreadth;
 }
 
 LayoutUnit LayoutGrid::gridAreaBreadthForChildIncludingAlignmentOffsets(const LayoutBox& child, GridTrackSizingDirection direction, const GridSizingData& sizingData) const
 {
     // We need the cached value when available because Content Distribution alignment properties
     // may have some influence in the final grid area breadth.
     const Vector<GridTrack>& tracks = (direction == ForColumns) ? sizingData.columnTracks : sizingData.rowTracks;
     const GridSpan& span = cachedGridSpan(child, direction);
     const Vector<LayoutUnit>& linePositions = (direction == ForColumns) ? m_columnPositions : m_rowPositions;
-    LayoutUnit initialTrackPosition = linePositions[span.resolvedInitialPosition.toInt()];
-    LayoutUnit finalTrackPosition = linePositions[span.resolvedFinalPosition.prev().toInt()];
+    LayoutUnit initialTrackPosition = linePositions[span.resolvedInitialPosition().toInt()];
+    LayoutUnit finalTrackPosition = linePositions[span.resolvedFinalPosition().prev().toInt()];
     // Track Positions vector stores the 'start' grid line of each track, so w have to add last track's baseSize.
-    return finalTrackPosition - initialTrackPosition + tracks[span.resolvedFinalPosition.prev().toInt()].baseSize();
+    return finalTrackPosition - initialTrackPosition + tracks[span.resolvedFinalPosition().prev().toInt()].baseSize();
 }
 
 void LayoutGrid::populateGridPositions(GridSizingData& sizingData)
 {
     // Since we add alignment offsets and track gutters, grid lines are not always adjacent. Hence we will have to
     // assume from now on that we just store positions of the initial grid lines of each track,
     // except the last one, which is the only one considered as a final grid line of a track.
     // FIXME: This will affect the computed style value of grid tracks size, since we are
     // using these positions to compute them.
 
@@ skipping 286 matching lines @@
 
 static inline LayoutUnit offsetBetweenTracks(ContentDistributionType distribution, const Vector<LayoutUnit>& trackPositions, const LayoutUnit& childBreadth)
 {
     return (distribution == ContentDistributionStretch || ContentDistributionStretch == ContentDistributionDefault) ? LayoutUnit() : trackPositions[1] - trackPositions[0] - childBreadth;
 
 }
 
 LayoutUnit LayoutGrid::columnAxisOffsetForChild(const LayoutBox& child) const
 {
     const GridSpan& rowsSpan = cachedGridSpan(child, ForRows);
-    size_t childStartLine = rowsSpan.resolvedInitialPosition.toInt();
+    size_t childStartLine = rowsSpan.resolvedInitialPosition().toInt();
     LayoutUnit startOfRow = m_rowPositions[childStartLine];
     LayoutUnit startPosition = startOfRow + marginBeforeForChild(child);
     if (hasAutoMarginsInColumnAxis(child))
         return startPosition;
     GridAxisPosition axisPosition = columnAxisPositionForChild(child);
     switch (axisPosition) {
     case GridAxisStart:
         return startPosition;
     case GridAxisEnd:
     case GridAxisCenter: {
-        size_t childEndLine = rowsSpan.resolvedFinalPosition.toInt();
+        size_t childEndLine = rowsSpan.resolvedFinalPosition().toInt();
         LayoutUnit endOfRow = m_rowPositions[childEndLine];
         // m_rowPositions include gutters so we need to substract them to get the actual end position for a given
         // row (this does not have to be done for the last track as there are no more m_rowPositions after it)
         if (childEndLine < m_rowPositions.size() - 1)
             endOfRow -= guttersSize(ForRows, 2);
         LayoutUnit childBreadth = child.logicalHeight() + child.marginLogicalHeight();
         if (childEndLine - childStartLine > 1 && childEndLine < m_rowPositions.size() - 1)
             endOfRow -= offsetBetweenTracks(styleRef().alignContentDistribution(), m_rowPositions, childBreadth);
         LayoutUnit offsetFromStartPosition = computeOverflowAlignmentOffset(child.styleRef().alignSelfOverflowAlignment(), endOfRow - startOfRow, childBreadth);
         return startPosition + (axisPosition == GridAxisEnd ? offsetFromStartPosition : offsetFromStartPosition / 2);
     }
     }
 
     ASSERT_NOT_REACHED();
     return 0;
 }
 
 LayoutUnit LayoutGrid::rowAxisOffsetForChild(const LayoutBox& child) const
 {
     const GridSpan& columnsSpan = cachedGridSpan(child, ForColumns);
-    size_t childStartLine = columnsSpan.resolvedInitialPosition.toInt();
+    size_t childStartLine = columnsSpan.resolvedInitialPosition().toInt();
     LayoutUnit startOfColumn = m_columnPositions[childStartLine];
     LayoutUnit startPosition = startOfColumn + marginStartForChild(child);
     if (hasAutoMarginsInRowAxis(child))
         return startPosition;
     GridAxisPosition axisPosition = rowAxisPositionForChild(child);
     switch (axisPosition) {
     case GridAxisStart:
         return startPosition;
     case GridAxisEnd:
     case GridAxisCenter: {
-        size_t childEndLine = columnsSpan.resolvedFinalPosition.toInt();
+        size_t childEndLine = columnsSpan.resolvedFinalPosition().toInt();
         LayoutUnit endOfColumn = m_columnPositions[childEndLine];
         // m_columnPositions include gutters so we need to substract them to get the actual end position for a given
         // column (this does not have to be done for the last track as there are no more m_columnPositions after it)
         if (childEndLine < m_columnPositions.size() - 1)
             endOfColumn -= guttersSize(ForRows, 2);
         LayoutUnit childBreadth = child.logicalWidth() + child.marginLogicalWidth();
         if (childEndLine - childStartLine > 1 && childEndLine < m_columnPositions.size() - 1)
             endOfColumn -= offsetBetweenTracks(styleRef().justifyContentDistribution(), m_columnPositions, childBreadth);
         LayoutUnit offsetFromStartPosition = computeOverflowAlignmentOffset(child.styleRef().justifySelfOverflowAlignment(), endOfColumn - startOfColumn, childBreadth);
         return startPosition + (axisPosition == GridAxisEnd ? offsetFromStartPosition : offsetFromStartPosition / 2);
@@ skipping 130 matching lines @@
 
     return LayoutPoint(rowAxisOffset, columnAxisOffsetForChild(child));
 }
 
 void LayoutGrid::paintChildren(const PaintInfo& paintInfo, const LayoutPoint& paintOffset) const
 {
     GridPainter(*this).paintChildren(paintInfo, paintOffset);
 }
 
 } // namespace blink