[LayoutNG] Split LayoutOpportunityIterator into separate file

third_party/WebKit/Source/core/layout/ng/ng_layout_opportunity_iterator.h

+// Copyright 2016 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.
+
+#ifndef NGLayoutOpportunityIterator_h
+#define NGLayoutOpportunityIterator_h
+
+#include "core/CoreExport.h"
+#include "core/layout/LayoutBox.h"
+#include "core/layout/ng/ng_constraint_space.h"
+#include "platform/heap/Handle.h"
+#include "wtf/text/WTFString.h"
+#include "wtf/Vector.h"
+
+namespace blink {
+
+class CORE_EXPORT NGLayoutOpportunityIterator final
+    : public GarbageCollectedFinalized<NGLayoutOpportunityIterator> {
+ public:
+  NGLayoutOpportunityIterator(NGConstraintSpace* space,
+                              unsigned clear,
+                              bool for_inline_or_bfc);
+  ~NGLayoutOpportunityIterator() {}
+
+  NGConstraintSpace* Next();
+
+  DEFINE_INLINE_VIRTUAL_TRACE() {
+    visitor->trace(constraint_space_);
+    visitor->trace(current_opportunities_);
+  }
+
+ private:
+  void computeForExclusion(unsigned index);
+  LayoutUnit heightForOpportunity(LayoutUnit left,
+                                  LayoutUnit top,
+                                  LayoutUnit right,
+                                  LayoutUnit bottom);
+  void addLayoutOpportunity(LayoutUnit left,
+                            LayoutUnit top,
+                            LayoutUnit right,
+                            LayoutUnit bottom);
+
+  Member<NGConstraintSpace> constraint_space_;
+  unsigned clear_;
+  bool for_inline_or_bfc_;
+  Vector<NGExclusion> filtered_exclusions_;
+  HeapVector<Member<NGConstraintSpace>> current_opportunities_;
+  unsigned current_exclusion_idx_;
+};
+
+}  // namespace blink
+
+#endif  // NGLayoutOpportunityIterator_h