Sibling invalidation sets

Source/core/css/invalidation/DescendantInvalidationSet.h

 /*
  * Copyright (C) 2014 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 48 matching lines @@
 
     bool invalidatesElement(Element&) const;
 
     void combine(const DescendantInvalidationSet& other);
 
     void addClass(const AtomicString& className);
     void addId(const AtomicString& id);
     void addTagName(const AtomicString& tagName);
     void addAttribute(const AtomicString& attributeLocalName);
 
+    const DescendantInvalidationSet* descendants() const { return m_descendantInvalidationSet.get(); }
+
+    DescendantInvalidationSet& ensureDescendantInvalidationSet();
+
+    void setSiblingInvalid() { m_siblingInvalid = true; }
+    bool siblingInvalid() const { return m_siblingInvalid; }
+
     void setWholeSubtreeInvalid();
     bool wholeSubtreeInvalid() const { return m_allDescendantsMightBeInvalid; }
 
     void setTreeBoundaryCrossing() { m_treeBoundaryCrossing = true; }
     bool treeBoundaryCrossing() const { return m_treeBoundaryCrossing; }
 
     void setInsertionPointCrossing() { m_insertionPointCrossing = true; }
     bool insertionPointCrossing() const { return m_insertionPointCrossing; }
 
     void setCustomPseudoInvalid() { m_customPseudoInvalid = true; }
     bool customPseudoInvalid() const { return m_customPseudoInvalid; }
 
+    unsigned maxDirectAdjacentSelectors() const { return m_maxDirectAdjacentSelectors; }
+    void setMaxDirectAdjacentSelectors(unsigned value) { m_maxDirectAdjacentSelectors = std::max(value, m_maxDirectAdjacentSelectors); }
+
     bool isEmpty() const { return !m_classes && !m_ids && !m_tagNames && !m_attributes && !m_customPseudoInvalid; }
 
     DECLARE_TRACE();
 
     void toTracedValue(TracedValue*) const;
 
 #ifndef NDEBUG
     void show() const;
 #endif
 
 private:
     DescendantInvalidationSet();
 
     WillBeHeapHashSet<AtomicString>& ensureClassSet();
     WillBeHeapHashSet<AtomicString>& ensureIdSet();
     WillBeHeapHashSet<AtomicString>& ensureTagNameSet();
     WillBeHeapHashSet<AtomicString>& ensureAttributeSet();
 
     // FIXME: optimize this if it becomes a memory issue.
     OwnPtrWillBeMember<WillBeHeapHashSet<AtomicString>> m_classes;
     OwnPtrWillBeMember<WillBeHeapHashSet<AtomicString>> m_ids;
     OwnPtrWillBeMember<WillBeHeapHashSet<AtomicString>> m_tagNames;
     OwnPtrWillBeMember<WillBeHeapHashSet<AtomicString>> m_attributes;
 
+    // Only for sibling invalidation sets, indicates the maximum possible number of siblings affected.
+    unsigned m_maxDirectAdjacentSelectors;
+
+    // Only for sibling invalidation sets, indicates the descendants of siblings.
+    RefPtrWillBeMember<DescendantInvalidationSet> m_descendantInvalidationSet;

[rune, 2015/09/01 15:56:46]

Does this mean that if this is the sibling invalidation set for .a, and you have
the following selectors:

.a + .b .c {}
.a + span + .d .e {}

you will have one descendant invalidation set for .b containing .c, one
descendant invalidation set for .d containing .e, and a third descendant
invalidation set pointed to here which combines .b and .d into a set which
contains both .c and .e?

+
+    // Only for sibling invalidation sets, indicates the sibling itself is invalid.
+    unsigned m_siblingInvalid : 1;
+
     // If true, all descendants might be invalidated, so a full subtree recalc is required.
     unsigned m_allDescendantsMightBeInvalid : 1;
 
     // If true, all descendants which are custom pseudo elements must be invalidated.
     unsigned m_customPseudoInvalid : 1;
 
     // If true, the invalidation must traverse into ShadowRoots with this set.
     unsigned m_treeBoundaryCrossing : 1;
 
     // If true, insertion point descendants must be invalidated.
     unsigned m_insertionPointCrossing : 1;
+
+    friend class RuleFeatureSetTest;
 };
 
+using InvalidationSetVector = WillBeHeapVector<RefPtrWillBeMember<DescendantInvalidationSet>, 8>;
+
 } // namespace blink
 
 #endif // DescendantInvalidationSet_h