Sibling invalidation sets

Source/core/css/invalidation/InvalidationSet.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 27 matching lines @@
 #include "wtf/RefCounted.h"
 #include "wtf/RefPtr.h"
 #include "wtf/text/AtomicStringHash.h"
 #include "wtf/text/StringHash.h"
 
 namespace blink {
 
 class Element;
 class TracedValue;
 
-// Tracks data to determine which elements of a DOM subtree need to have style
-// recalculated.
+// Tracks data to determine which descendants in a DOM subtree, or
+// siblings and their descendants, need to have style recalculated.
 class CORE_EXPORT InvalidationSet final : public RefCountedWillBeGarbageCollected<InvalidationSet> {
     WTF_MAKE_NONCOPYABLE(InvalidationSet);
 public:
     static PassRefPtrWillBeRawPtr<InvalidationSet> create()
     {
         return adoptRefWillBeNoop(new InvalidationSet);
     }
 
     static void cacheTracingFlag();
 
     bool invalidatesElement(Element&) const;
 
     void combine(const InvalidationSet& other);
 
     void addClass(const AtomicString& className);
     void addId(const AtomicString& id);
     void addTagName(const AtomicString& tagName);
     void addAttribute(const AtomicString& attributeLocalName);
 
+    const InvalidationSet* descendants() const { return m_descendantInvalidationSet.get(); }
+
+    InvalidationSet& ensureDescendantInvalidationSet();
+
     void setWholeSubtreeInvalid();
     bool wholeSubtreeInvalid() const { return m_allDescendantsMightBeInvalid; }
 
     void setInvalidatesSelf() { m_invalidatesSelf = true; }
     bool invalidatesSelf() const { return m_invalidatesSelf; }
 
     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 updateMaxDirectAdjacentSelectors(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
 
@@ skipping 18 matching lines @@
     unsigned m_invalidatesSelf : 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;
+
+    // Only for sibling invalidation sets, indicates the maximum possible number of siblings affected.
+    unsigned m_maxDirectAdjacentSelectors;

[rune, 2015/10/02 13:17:59]

Can we use sub-classing instead?

SiblingInvalidationSet sub-class which adds these members.

In particular, I think that the code in addFeaturesToInvalidationSets would be
easier to read and understand if you had

class InvalidationSet { ... }

class DescendantInvalidationSet : public InvalidationSet {
    /* nothing added, just to have a separate type to make things clearer */
}

class SiblingInvalidationSet : public InvalidationSet
{
    maxDirectAdjacentSelectors;
    DescendantInvalidationSet m_descendantInvalidationSet
}

[Eric Willigers, 2015/10/14 00:25:40]

Done.

+
+    // Only for sibling invalidation sets, indicates the descendants of siblings.
+    RefPtrWillBeMember<InvalidationSet> m_descendantInvalidationSet;
+
+    friend class RuleFeatureSetTest;
+};
+
+using InvalidationSetVector = WillBeHeapVector<RefPtrWillBeMember<InvalidationSet>>;
+
+struct InvalidationLists {
+    STACK_ALLOCATED();
+
+    InvalidationSetVector descendants;
+    InvalidationSetVector siblings;
 };
 
 } // namespace blink
 
 #endif // InvalidationSet_h