[css-grid] Move the track sizing algorithm to its own class

third_party/WebKit/Source/core/layout/Grid.h

Index: third_party/WebKit/Source/core/layout/Grid.h
diff --git a/third_party/WebKit/Source/core/layout/Grid.h b/third_party/WebKit/Source/core/layout/Grid.h
new file mode 100644
index 0000000000000000000000000000000000000000..d113f967970d7eaf4e18d9baea4da4d895c4592d
--- /dev/null
+++ b/third_party/WebKit/Source/core/layout/Grid.h
@@ -0,0 +1,124 @@
+#ifndef Grid_h

[Manuel Rego, 2017/01/30 11:00:45]

I guess you miss the license header here. And in the rest of files of this patch
too.

[svillar, 2017/01/30 11:28:28]

Acknowledged.

+#define Grid_h
+
+#include "core/layout/OrderIterator.h"
+#include "core/style/GridArea.h"
+#include "core/style/GridPositionsResolver.h"
+#include "wtf/Assertions.h"
+#include "wtf/ListHashSet.h"
+#include "wtf/Vector.h"
+
+namespace blink {
+
+typedef Vector<LayoutBox*, 1> GridCell;

[jfernandez, 2017/01/30 08:48:48]

Can those LayoutBox pointer be null ? Perhaps we can use references.

[svillar, 2017/01/30 09:35:45]

Right, but I guess we can do it in a follow up change. Otherwise we would have
to change many other things instead of moving code around.

[Manuel Rego, 2017/01/30 11:00:45]

Then add a TODO so we don't forget about it. :-)

+typedef Vector<Vector<GridCell>> GridAsMatrix;
+typedef ListHashSet<size_t> OrderedTrackIndexSet;
+
+class LayoutGrid;
+
+// TODO(svillar): move into this class once GridIterator is added.

[jfernandez, 2017/01/30 08:48:48]

I don't understand this comment. 

[svillar, 2017/01/30 09:35:45]

That's a legacy comment, I'll change it.

+class Grid final {

[Manuel Rego, 2017/01/30 11:00:45]

Please add a brief comment explaining what's the purpose of this class.
People might get confused with LayoutGrid and Grid.

+ public:
+  Grid(const LayoutGrid*);

[jfernandez, 2017/01/30 08:48:48]

Could we use reference here ?

[svillar, 2017/01/30 09:35:45]

I tried but it looks like we cannot because in computeIntrinsicLogicalWidths we
need to pass the "this" const pointer.

+
+  size_t numTracks(GridTrackSizingDirection) const;
+
+  void ensureGridSize(size_t maximumRowSize, size_t maximumColumnSize);
+  void insert(LayoutBox&, const GridArea&);
+
+  // Note that out of flow children are not grid items.
+  bool hasGridItems() const { return !m_gridItemArea.isEmpty(); }
+
+  bool hasAnyOrthogonalGridItem() const { return m_hasAnyOrthogonalGridItem; }
+  void setHasAnyOrthogonalGridItem(bool);

[Manuel Rego, 2017/01/30 11:00:45]

This method could be implemented here, like the previous one.

[svillar, 2017/01/30 11:28:28]

Nop because it'd break the rule of not having implementations except oneliners
in the header file. Note that due to the weird chromium style it's difficult to
get oneliners with long names.

+
+  GridArea gridItemArea(const LayoutBox& item) const;

[jfernandez, 2017/01/30 08:48:48]

We don't need the "item" arg name.

[svillar, 2017/01/30 09:35:45]

Acknowledged.

+  void setGridItemArea(const LayoutBox& item, GridArea);

[jfernandez, 2017/01/30 08:48:48]

Ditto

+
+  GridSpan gridItemSpan(const LayoutBox&, GridTrackSizingDirection) const;
+
+  size_t gridItemPaintOrder(const LayoutBox& item) const;
+  void setGridItemPaintOrder(const LayoutBox& item, size_t order);
+
+  const GridCell& cell(size_t row, size_t column) const {
+    return m_grid[row][column];
+  }
+
+  int smallestTrackStart(GridTrackSizingDirection) const;
+  void setSmallestTracksStart(int rowStart, int columnStart);
+
+  size_t autoRepeatTracks(GridTrackSizingDirection) const;
+  void setAutoRepeatTracks(size_t autoRepeatRows, size_t autoRepeatColumns);
+
+  typedef ListHashSet<size_t> OrderedTrackIndexSet;
+  void setAutoRepeatEmptyColumns(std::unique_ptr<OrderedTrackIndexSet>);
+  void setAutoRepeatEmptyRows(std::unique_ptr<OrderedTrackIndexSet>);
+
+  size_t autoRepeatEmptyTracksCount(GridTrackSizingDirection) const;
+  bool hasAutoRepeatEmptyTracks(GridTrackSizingDirection) const;
+  bool isEmptyAutoRepeatTrack(GridTrackSizingDirection, size_t) const;
+
+  OrderedTrackIndexSet* autoRepeatEmptyTracks(GridTrackSizingDirection) const;
+
+  OrderIterator& orderIterator() { return m_orderIterator; }
+
+  void setNeedsItemsPlacement(bool);
+  bool needsItemsPlacement() const { return m_needsItemsPlacement; };
+
+#if DCHECK_IS_ON()
+  bool hasAnyGridItemPaintOrder() const;
+#endif
+
+ private:
+  friend class GridIterator;
+
+  OrderIterator m_orderIterator;
+
+  int m_smallestColumnStart{0};
+  int m_smallestRowStart{0};
+
+  size_t m_autoRepeatColumns{0};
+  size_t m_autoRepeatRows{0};
+
+  bool m_hasAnyOrthogonalGridItem{false};
+  bool m_needsItemsPlacement{true};
+
+  GridAsMatrix m_grid;
+
+  HashMap<const LayoutBox*, GridArea> m_gridItemArea;
+  HashMap<const LayoutBox*, size_t> m_gridItemsIndexesMap;

[jfernandez, 2017/01/30 08:48:48]

Ditton about LayoutBox pointers.

[svillar, 2017/01/30 09:35:45]

Same comment here, perhaps for a followup change.

[Manuel Rego, 2017/01/30 11:00:45]

I think for the HashMap we need pointers, but maybe I'm wrong.

[svillar, 2017/01/30 11:28:28]

Indeed, we cannot have references in the HashMap

+
+  std::unique_ptr<OrderedTrackIndexSet> m_autoRepeatEmptyColumns{nullptr};
+  std::unique_ptr<OrderedTrackIndexSet> m_autoRepeatEmptyRows{nullptr};
+};
+
+class GridIterator {
+  WTF_MAKE_NONCOPYABLE(GridIterator);
+
+ public:
+  // |direction| is the direction that is fixed to |fixedTrackIndex| so e.g
+  // GridIterator(m_grid, ForColumns, 1) will walk over the rows of the 2nd
+  // column.
+  GridIterator(const Grid&,
+               GridTrackSizingDirection,
+               size_t fixedTrackIndex,
+               size_t varyingTrackIndex = 0);
+
+  LayoutBox* nextGridItem();
+
+  bool checkEmptyCells(size_t rowSpan, size_t columnSpan) const;
+
+  std::unique_ptr<GridArea> nextEmptyGridArea(size_t fixedTrackSpan,
+                                              size_t varyingTrackSpan);
+
+ private:
+  const GridAsMatrix& m_grid;
+  GridTrackSizingDirection m_direction;
+  size_t m_rowIndex;
+  size_t m_columnIndex;
+  size_t m_childIndex;
+};
+
+}  // namespace blink
+
+#endif  // Grid_h