Setting up OrderIterator shouldn't require an extra Vector

Source/core/rendering/RenderGrid.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 644 matching lines @@
         ASSERT(!specifiedMajorAxisAutoGridItems.size());
         return;
     }
 
     placeSpecifiedMajorAxisItemsOnGrid(specifiedMajorAxisAutoGridItems);
     placeAutoMajorAxisItemsOnGrid(autoMajorAxisAutoGridItems);
 }
 
 void RenderGrid::populateExplicitGridAndOrderIterator()
 {
-    // FIXME: We should find a way to share OrderIterator's Vector's
-    // initialization code with RenderFlexibleBox.
-    Vector<int> orderValues;
-    bool anyChildHasDefaultOrderValue = false;
+    OrderIteratorPopulator populator(m_orderIterator);
 
     size_t maximumRowIndex = std::max<size_t>(1, explicitGridRowCount());
     size_t maximumColumnIndex = std::max<size_t>(1, explicitGridColumnCount());
 
     for (RenderBox* child = firstChildBox(); child; child = child->nextSiblingBox()) {
-        // Avoid growing the vector for the common-case default value of 0.
-        if (int order = child->style()->order())
-            orderValues.append(child->style()->order());
-        else
-            anyChildHasDefaultOrderValue = true;
+        populator.collectChild(child);
 
         // This function bypasses the cache (cachedGridCoordinate()) as it is used to build it.
         OwnPtr<GridSpan> rowPositions = resolveGridPositionsFromStyle(child, ForRows);
         OwnPtr<GridSpan> columnPositions = resolveGridPositionsFromStyle(child, ForColumns);
 
         // |positions| is 0 if we need to run the auto-placement algorithm. Our estimation ignores
         // this case as the auto-placement algorithm will grow the grid as needed.
         if (rowPositions)
             maximumRowIndex = std::max(maximumRowIndex, rowPositions->finalPositionIndex + 1);
         if (columnPositions)
             maximumColumnIndex = std::max(maximumColumnIndex, columnPositions->finalPositionIndex + 1);
     }
 
     m_grid.grow(maximumRowIndex);
     for (size_t i = 0; i < m_grid.size(); ++i)
         m_grid[i].grow(maximumColumnIndex);
-
-    if (anyChildHasDefaultOrderValue) {
-        // Avoid growing the vector to the default capacity of 16 if we're only going to put one item in it.
-        if (orderValues.isEmpty())
-            orderValues.reserveInitialCapacity(1);
-        orderValues.append(0);
-    }
-
-    m_orderIterator.setOrderValues(orderValues);
 }
 
 void RenderGrid::placeSpecifiedMajorAxisItemsOnGrid(Vector<RenderBox*> autoGridItems)
 {
     for (size_t i = 0; i < autoGridItems.size(); ++i) {
         OwnPtr<GridSpan> majorAxisPositions = resolveGridPositionsFromStyle(autoGridItems[i], autoPlacementMajorAxisDirection());
         GridIterator iterator(m_grid, autoPlacementMajorAxisDirection(), majorAxisPositions->initialPositionIndex);
         if (OwnPtr<GridCoordinate> emptyGridArea = iterator.nextEmptyGridArea()) {
             insertItemIntoGrid(autoGridItems[i], emptyGridArea->rows.initialPositionIndex, emptyGridArea->columns.initialPositionIndex);
             continue;
@@ skipping 353 matching lines @@
     if (isOutOfFlowPositioned())
         return "RenderGrid (positioned)";
     if (isAnonymous())
         return "RenderGrid (generated)";
     if (isRelPositioned())
         return "RenderGrid (relative positioned)";
     return "RenderGrid";
 }
 
 } // namespace WebCore