[css-grid] Simplify GridResolvedPosition interface

third_party/WebKit/Source/core/style/GridResolvedPosition.cpp

Index: third_party/WebKit/Source/core/style/GridResolvedPosition.cpp
diff --git a/third_party/WebKit/Source/core/style/GridResolvedPosition.cpp b/third_party/WebKit/Source/core/style/GridResolvedPosition.cpp
index de459cf8f3e9c912e9c795c26da2cb0e670fd8a9..6b8dc9498b2c4ae80f7dcc27618f2b1a2c4761ac 100644
--- a/third_party/WebKit/Source/core/style/GridResolvedPosition.cpp
+++ b/third_party/WebKit/Source/core/style/GridResolvedPosition.cpp
@@ -37,7 +37,7 @@ GridPositionSide GridResolvedPosition::finalPositionSide(GridTrackSizingDirectio
     return (direction == ForColumns) ? ColumnEndSide : RowEndSide;
 }
 
-void GridResolvedPosition::initialAndFinalPositionsFromStyle(const ComputedStyle& gridContainerStyle, const LayoutBox& gridItem, GridTrackSizingDirection direction, GridPosition& initialPosition, GridPosition& finalPosition)
+static void initialAndFinalPositionsFromStyle(const ComputedStyle& gridContainerStyle, const LayoutBox& gridItem, GridTrackSizingDirection direction, GridPosition& initialPosition, GridPosition& finalPosition)
 {
     initialPosition = (direction == ForColumns) ? gridItem.style()->gridColumnStart() : gridItem.style()->gridRowStart();
     finalPosition = (direction == ForColumns) ? gridItem.style()->gridColumnEnd() : gridItem.style()->gridRowEnd();
@@ -49,10 +49,10 @@ void GridResolvedPosition::initialAndFinalPositionsFromStyle(const ComputedStyle
 
     // Try to early detect the case of non existing named grid lines. This way we could assume later that
     // GridResolvedPosition::resolveGrisPositionFromStyle() always return a valid resolved position.
-    if (initialPosition.isNamedGridArea() && !isValidNamedLineOrArea(initialPosition.namedGridLine(), gridContainerStyle, initialPositionSide(direction)))
+    if (initialPosition.isNamedGridArea() && !GridResolvedPosition::isValidNamedLineOrArea(initialPosition.namedGridLine(), gridContainerStyle, GridResolvedPosition::initialPositionSide(direction)))
         initialPosition.setAutoPosition();
 
-    if (finalPosition.isNamedGridArea() && !isValidNamedLineOrArea(finalPosition.namedGridLine(), gridContainerStyle, finalPositionSide(direction)))
+    if (finalPosition.isNamedGridArea() && !GridResolvedPosition::isValidNamedLineOrArea(finalPosition.namedGridLine(), gridContainerStyle, GridResolvedPosition::finalPositionSide(direction)))
         finalPosition.setAutoPosition();
 
     // If the grid item has an automatic position and a grid span for a named line in a given dimension, instead treat the grid span as one.
@@ -62,58 +62,114 @@ void GridResolvedPosition::initialAndFinalPositionsFromStyle(const ComputedStyle
         initialPosition.setSpanPosition(1, String());
 }
 
-GridSpan GridResolvedPosition::resolveGridPositionsFromAutoPlacementPosition(const ComputedStyle& gridContainerStyle, const LayoutBox& gridItem, GridTrackSizingDirection direction, const GridResolvedPosition& resolvedInitialPosition)
+static GridSpan definiteGridSpanWithInitialNamedSpanAgainstOpposite(const GridResolvedPosition& resolvedOppositePosition, const GridPosition& position, const Vector<size_t>& gridLines)
 {
-    GridPosition initialPosition, finalPosition;
-    initialAndFinalPositionsFromStyle(gridContainerStyle, gridItem, direction, initialPosition, finalPosition);
-
-    GridPositionSide finalSide = finalPositionSide(direction);
+    if (resolvedOppositePosition == 0)
+        return GridSpan::definiteGridSpan(resolvedOppositePosition, resolvedOppositePosition.next());
 
-    // This method will only be used when both positions need to be resolved against the opposite one.
-    ASSERT(initialPosition.shouldBeResolvedAgainstOppositePosition() && finalPosition.shouldBeResolvedAgainstOppositePosition());
+    size_t firstLineBeforeOppositePositionIndex = 0;
+    const size_t* firstLineBeforeOppositePosition = std::lower_bound(gridLines.begin(), gridLines.end(), resolvedOppositePosition.toInt());
+    if (firstLineBeforeOppositePosition != gridLines.end())
+        firstLineBeforeOppositePositionIndex = firstLineBeforeOppositePosition - gridLines.begin();
+    size_t gridLineIndex = std::max<int>(0, firstLineBeforeOppositePositionIndex - position.spanPosition());
+    GridResolvedPosition resolvedGridLinePosition = GridResolvedPosition(gridLines[gridLineIndex]);
+    if (resolvedGridLinePosition >= resolvedOppositePosition)
+        resolvedGridLinePosition = resolvedOppositePosition.prev();
+    return GridSpan::definiteGridSpan(resolvedGridLinePosition, resolvedOppositePosition);
+}
 
-    GridResolvedPosition resolvedFinalPosition = resolvedInitialPosition.next();
+static GridSpan definiteGridSpanWithFinalNamedSpanAgainstOpposite(const GridResolvedPosition& resolvedOppositePosition, const GridPosition& position, const Vector<size_t>& gridLines)
+{
+    size_t firstLineAfterOppositePositionIndex = gridLines.size() - 1;
+    const size_t* firstLineAfterOppositePosition = std::upper_bound(gridLines.begin(), gridLines.end(), resolvedOppositePosition.toInt());
+    if (firstLineAfterOppositePosition != gridLines.end())
+        firstLineAfterOppositePositionIndex = firstLineAfterOppositePosition - gridLines.begin();
+    size_t gridLineIndex = std::min(gridLines.size() - 1, firstLineAfterOppositePositionIndex + position.spanPosition() - 1);
+    GridResolvedPosition resolvedGridLinePosition = gridLines[gridLineIndex];
+    if (resolvedGridLinePosition <= resolvedOppositePosition)
+        resolvedGridLinePosition = resolvedOppositePosition.next();
+
+    return GridSpan::definiteGridSpan(resolvedOppositePosition, resolvedGridLinePosition);
+}
 
-    if (initialPosition.isSpan())
-        return resolveGridPositionAgainstOppositePosition(gridContainerStyle, resolvedInitialPosition, initialPosition, finalSide);
-    if (finalPosition.isSpan())
-        return resolveGridPositionAgainstOppositePosition(gridContainerStyle, resolvedInitialPosition, finalPosition, finalSide);
+static GridSpan definiteGridSpanWithNamedSpanAgainstOpposite(const GridResolvedPosition& resolvedOppositePosition, const GridPosition& position, GridPositionSide side, const Vector<size_t>& gridLines)
+{
+    if (side == RowStartSide || side == ColumnStartSide)
+        return definiteGridSpanWithInitialNamedSpanAgainstOpposite(resolvedOppositePosition, position, gridLines);
 
-    return GridSpan::definiteGridSpan(resolvedInitialPosition, resolvedFinalPosition);
+    return definiteGridSpanWithFinalNamedSpanAgainstOpposite(resolvedOppositePosition, position, gridLines);
 }
 
-GridSpan GridResolvedPosition::resolveGridPositionsFromStyle(const ComputedStyle& gridContainerStyle, const LayoutBox& gridItem, GridTrackSizingDirection direction)
+static GridSpan resolveNamedGridLinePositionAgainstOppositePosition(const ComputedStyle& gridContainerStyle, const GridResolvedPosition& resolvedOppositePosition, const GridPosition& position, GridPositionSide side)
 {
-    GridPosition initialPosition, finalPosition;
-    initialAndFinalPositionsFromStyle(gridContainerStyle, gridItem, direction, initialPosition, finalPosition);
+    ASSERT(position.isSpan());
+    ASSERT(!position.namedGridLine().isNull());
+    // Negative positions are not allowed per the specification and should have been handled during parsing.
+    ASSERT(position.spanPosition() > 0);
 
-    GridPositionSide initialSide = initialPositionSide(direction);
-    GridPositionSide finalSide = finalPositionSide(direction);
+    const NamedGridLinesMap& gridLinesNames = gridLinesForSide(gridContainerStyle, side);
+    NamedGridLinesMap::const_iterator it = gridLinesNames.find(position.namedGridLine());
 
-    if (initialPosition.shouldBeResolvedAgainstOppositePosition() && finalPosition.shouldBeResolvedAgainstOppositePosition()) {
-        // We can't get our grid positions without running the auto placement algorithm.
-        return GridSpan::indefiniteGridSpan();
+    // If there is no named grid line of that name, we resolve the position to 'auto' (which is equivalent to 'span 1' in this case).
+    // See http://lists.w3.org/Archives/Public/www-style/2013Jun/0394.html.
+    if (it == gridLinesNames.end()) {
+        if ((side == ColumnStartSide || side == RowStartSide) && resolvedOppositePosition.toInt())
+            return GridSpan::definiteGridSpan(resolvedOppositePosition.prev(), resolvedOppositePosition);
+        return GridSpan::definiteGridSpan(resolvedOppositePosition, resolvedOppositePosition.next());
     }
 
-    if (initialPosition.shouldBeResolvedAgainstOppositePosition()) {
-        // Infer the position from the final position ('auto / 1' or 'span 2 / 3' case).
-        GridResolvedPosition finalResolvedPosition = resolveGridPositionFromStyle(gridContainerStyle, finalPosition, finalSide);
-        return resolveGridPositionAgainstOppositePosition(gridContainerStyle, finalResolvedPosition, initialPosition, initialSide);
+    return definiteGridSpanWithNamedSpanAgainstOpposite(resolvedOppositePosition, position, side, it->value);
+}
+
+static GridSpan definiteGridSpanWithSpanAgainstOpposite(const GridResolvedPosition& resolvedOppositePosition, const GridPosition& position, GridPositionSide side)
+{
+    size_t positionOffset = position.spanPosition();
+    if (side == ColumnStartSide || side == RowStartSide) {
+        if (resolvedOppositePosition == 0)
+            return GridSpan::definiteGridSpan(resolvedOppositePosition, resolvedOppositePosition.next());
+
+        GridResolvedPosition initialResolvedPosition = GridResolvedPosition(std::max<int>(0, resolvedOppositePosition.toInt() - positionOffset));
+        return GridSpan::definiteGridSpan(initialResolvedPosition, resolvedOppositePosition);
     }
 
-    if (finalPosition.shouldBeResolvedAgainstOppositePosition()) {
-        // Infer our position from the initial position ('1 / auto' or '3 / span 2' case).
-        GridResolvedPosition initialResolvedPosition = resolveGridPositionFromStyle(gridContainerStyle, initialPosition, initialSide);
-        return resolveGridPositionAgainstOppositePosition(gridContainerStyle, initialResolvedPosition, finalPosition, finalSide);
+    return GridSpan::definiteGridSpan(resolvedOppositePosition, GridResolvedPosition(resolvedOppositePosition.toInt() + positionOffset));
+}
+
+static GridSpan resolveGridPositionAgainstOppositePosition(const ComputedStyle& gridContainerStyle, const GridResolvedPosition& resolvedOppositePosition, const GridPosition& position, GridPositionSide side)
+{
+    if (position.isAuto()) {
+        if ((side == ColumnStartSide || side == RowStartSide) && resolvedOppositePosition.toInt())
+            return GridSpan::definiteGridSpan(resolvedOppositePosition.prev(), resolvedOppositePosition);
+        return GridSpan::definiteGridSpan(resolvedOppositePosition, resolvedOppositePosition.next());
     }
 
-    GridResolvedPosition resolvedInitialPosition = resolveGridPositionFromStyle(gridContainerStyle, initialPosition, initialSide);
-    GridResolvedPosition resolvedFinalPosition = resolveGridPositionFromStyle(gridContainerStyle, finalPosition, finalSide);
+    ASSERT(position.isSpan());
+    ASSERT(position.spanPosition() > 0);
 
-    if (resolvedFinalPosition < resolvedInitialPosition)
-        std::swap(resolvedFinalPosition, resolvedInitialPosition);
-    else if (resolvedFinalPosition == resolvedInitialPosition)
-        resolvedFinalPosition = resolvedInitialPosition.next();
+    if (!position.namedGridLine().isNull()) {
+        // span 2 'c' -> we need to find the appropriate grid line before / after our opposite position.
+        return resolveNamedGridLinePositionAgainstOppositePosition(gridContainerStyle, resolvedOppositePosition, position, side);
+    }
+
+    return definiteGridSpanWithSpanAgainstOpposite(resolvedOppositePosition, position, side);
+}
+
+GridSpan GridResolvedPosition::resolveGridPositionsFromAutoPlacementPosition(const ComputedStyle& gridContainerStyle, const LayoutBox& gridItem, GridTrackSizingDirection direction, const GridResolvedPosition& resolvedInitialPosition)
+{
+    GridPosition initialPosition, finalPosition;
+    initialAndFinalPositionsFromStyle(gridContainerStyle, gridItem, direction, initialPosition, finalPosition);
+
+    GridPositionSide finalSide = finalPositionSide(direction);
+
+    // This method will only be used when both positions need to be resolved against the opposite one.
+    ASSERT(initialPosition.shouldBeResolvedAgainstOppositePosition() && finalPosition.shouldBeResolvedAgainstOppositePosition());
+
+    GridResolvedPosition resolvedFinalPosition = resolvedInitialPosition.next();
+
+    if (initialPosition.isSpan())
+        return resolveGridPositionAgainstOppositePosition(gridContainerStyle, resolvedInitialPosition, initialPosition, finalSide);
+    if (finalPosition.isSpan())
+        return resolveGridPositionAgainstOppositePosition(gridContainerStyle, resolvedInitialPosition, finalPosition, finalSide);
 
     return GridSpan::definiteGridSpan(resolvedInitialPosition, resolvedFinalPosition);
 }
@@ -128,12 +184,12 @@ size_t GridResolvedPosition::explicitGridRowCount(const ComputedStyle& gridConta
     return std::min(gridContainerStyle.gridTemplateRows().size(), kGridMaxTracks);
 }
 
-size_t GridResolvedPosition::explicitGridSizeForSide(const ComputedStyle& gridContainerStyle, GridPositionSide side)
+static size_t explicitGridSizeForSide(const ComputedStyle& gridContainerStyle, GridPositionSide side)
 {
-    return (side == ColumnStartSide || side == ColumnEndSide) ? explicitGridColumnCount(gridContainerStyle) : explicitGridRowCount(gridContainerStyle);
+    return (side == ColumnStartSide || side == ColumnEndSide) ? GridResolvedPosition::explicitGridColumnCount(gridContainerStyle) : GridResolvedPosition::explicitGridRowCount(gridContainerStyle);
 }
 
-GridResolvedPosition GridResolvedPosition::resolveNamedGridLinePositionFromStyle(const ComputedStyle& gridContainerStyle, const GridPosition& position, GridPositionSide side)
+static GridResolvedPosition resolveNamedGridLinePositionFromStyle(const ComputedStyle& gridContainerStyle, const GridPosition& position, GridPositionSide side)
 {
     ASSERT(!position.namedGridLine().isNull());
 
@@ -154,7 +210,7 @@ GridResolvedPosition GridResolvedPosition::resolveNamedGridLinePositionFromStyle
     return it->value[namedGridLineIndex];
 }
 
-GridResolvedPosition GridResolvedPosition::resolveGridPositionFromStyle(const ComputedStyle& gridContainerStyle, const GridPosition& position, GridPositionSide side)
+static GridResolvedPosition resolveGridPositionFromStyle(const ComputedStyle& gridContainerStyle, const GridPosition& position, GridPositionSide side)
 {
     switch (position.type()) {
     case ExplicitPosition: {
@@ -182,7 +238,7 @@ GridResolvedPosition GridResolvedPosition::resolveGridPositionFromStyle(const Co
         // ''<custom-ident>-start (for grid-*-start) / <custom-ident>-end'' (for grid-*-end), contributes the first such
         // line to the grid item's placement.
         String namedGridLine = position.namedGridLine();
-        ASSERT(isValidNamedLineOrArea(namedGridLine, gridContainerStyle, side));
+        ASSERT(GridResolvedPosition::isValidNamedLineOrArea(namedGridLine, gridContainerStyle, side));
 
         const NamedGridLinesMap& gridLineNames = gridLinesForSide(gridContainerStyle, side);
         NamedGridLinesMap::const_iterator implicitLineIter = gridLineNames.find(implicitNamedGridLineForSide(namedGridLine, side));
@@ -211,44 +267,40 @@ GridResolvedPosition GridResolvedPosition::resolveGridPositionFromStyle(const Co
     return GridResolvedPosition(0);
 }
 
-GridSpan GridResolvedPosition::resolveGridPositionAgainstOppositePosition(const ComputedStyle& gridContainerStyle, const GridResolvedPosition& resolvedOppositePosition, const GridPosition& position, GridPositionSide side)
+GridSpan GridResolvedPosition::resolveGridPositionsFromStyle(const ComputedStyle& gridContainerStyle, const LayoutBox& gridItem, GridTrackSizingDirection direction)
 {
-    if (position.isAuto()) {
-        if ((side == ColumnStartSide || side == RowStartSide) && resolvedOppositePosition.toInt())
-            return GridSpan::definiteGridSpan(resolvedOppositePosition.prev(), resolvedOppositePosition);
-        return GridSpan::definiteGridSpan(resolvedOppositePosition, resolvedOppositePosition.next());
-    }
+    GridPosition initialPosition, finalPosition;
+    initialAndFinalPositionsFromStyle(gridContainerStyle, gridItem, direction, initialPosition, finalPosition);
 
-    ASSERT(position.isSpan());
-    ASSERT(position.spanPosition() > 0);
+    GridPositionSide initialSide = initialPositionSide(direction);
+    GridPositionSide finalSide = finalPositionSide(direction);
 
-    if (!position.namedGridLine().isNull()) {
-        // span 2 'c' -> we need to find the appropriate grid line before / after our opposite position.
-        return resolveNamedGridLinePositionAgainstOppositePosition(gridContainerStyle, resolvedOppositePosition, position, side);
+    if (initialPosition.shouldBeResolvedAgainstOppositePosition() && finalPosition.shouldBeResolvedAgainstOppositePosition()) {
+        // We can't get our grid positions without running the auto placement algorithm.
+        return GridSpan::indefiniteGridSpan();
     }
 
-    return GridSpan::definiteGridSpanWithSpanAgainstOpposite(resolvedOppositePosition, position, side);
-}
+    if (initialPosition.shouldBeResolvedAgainstOppositePosition()) {
+        // Infer the position from the final position ('auto / 1' or 'span 2 / 3' case).
+        GridResolvedPosition finalResolvedPosition = resolveGridPositionFromStyle(gridContainerStyle, finalPosition, finalSide);
+        return resolveGridPositionAgainstOppositePosition(gridContainerStyle, finalResolvedPosition, initialPosition, initialSide);
+    }
 
-GridSpan GridResolvedPosition::resolveNamedGridLinePositionAgainstOppositePosition(const ComputedStyle& gridContainerStyle, const GridResolvedPosition& resolvedOppositePosition, const GridPosition& position, GridPositionSide side)
-{
-    ASSERT(position.isSpan());
-    ASSERT(!position.namedGridLine().isNull());
-    // Negative positions are not allowed per the specification and should have been handled during parsing.
-    ASSERT(position.spanPosition() > 0);
+    if (finalPosition.shouldBeResolvedAgainstOppositePosition()) {
+        // Infer our position from the initial position ('1 / auto' or '3 / span 2' case).
+        GridResolvedPosition initialResolvedPosition = resolveGridPositionFromStyle(gridContainerStyle, initialPosition, initialSide);
+        return resolveGridPositionAgainstOppositePosition(gridContainerStyle, initialResolvedPosition, finalPosition, finalSide);
+    }
 
-    const NamedGridLinesMap& gridLinesNames = gridLinesForSide(gridContainerStyle, side);
-    NamedGridLinesMap::const_iterator it = gridLinesNames.find(position.namedGridLine());
+    GridResolvedPosition resolvedInitialPosition = resolveGridPositionFromStyle(gridContainerStyle, initialPosition, initialSide);
+    GridResolvedPosition resolvedFinalPosition = resolveGridPositionFromStyle(gridContainerStyle, finalPosition, finalSide);
 
-    // If there is no named grid line of that name, we resolve the position to 'auto' (which is equivalent to 'span 1' in this case).
-    // See http://lists.w3.org/Archives/Public/www-style/2013Jun/0394.html.
-    if (it == gridLinesNames.end()) {
-        if ((side == ColumnStartSide || side == RowStartSide) && resolvedOppositePosition.toInt())
-            return GridSpan::definiteGridSpan(resolvedOppositePosition.prev(), resolvedOppositePosition);
-        return GridSpan::definiteGridSpan(resolvedOppositePosition, resolvedOppositePosition.next());
-    }
+    if (resolvedFinalPosition < resolvedInitialPosition)
+        std::swap(resolvedFinalPosition, resolvedInitialPosition);
+    else if (resolvedFinalPosition == resolvedInitialPosition)
+        resolvedFinalPosition = resolvedInitialPosition.next();
 
-    return GridSpan::definiteGridSpanWithNamedSpanAgainstOpposite(resolvedOppositePosition, position, side, it->value);
+    return GridSpan::definiteGridSpan(resolvedInitialPosition, resolvedFinalPosition);
 }
 
 } // namespace blink