third_party/WebKit/Source/core/css/invalidation/InvalidationSet.h

/*
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#ifndef InvalidationSet_h
#define InvalidationSet_h

#include "core/CoreExport.h"
#include "wtf/Allocator.h"
#include "wtf/Assertions.h"
#include "wtf/Forward.h"
#include "wtf/HashSet.h"
#include "wtf/RefPtr.h"
#include "wtf/text/AtomicStringHash.h"
#include "wtf/text/StringHash.h"
#include <memory>

namespace blink {

class Element;
class TracedValue;

enum InvalidationType { InvalidateDescendants, InvalidateSiblings };

// Tracks data to determine which descendants in a DOM subtree, or
// siblings and their descendants, need to have style recalculated.
//
// Some example invalidation sets:
//
// .z {}
//   For class z we will have a DescendantInvalidationSet with invalidatesSelf
//   (the element itself is invalidated).
//
// .y .z {}
//   For class y we will have a DescendantInvalidationSet containing class z.
//
// .x ~ .z {}
//   For class x we will have a SiblingInvalidationSet containing class z, with
//   invalidatesSelf (the sibling itself is invalidated).
//
// .w ~ .y .z {}
//   For class w we will have a SiblingInvalidationSet containing class y, with
//   the SiblingInvalidationSet havings siblingDescendants containing class z.
//
// .v * {}
//   For class v we will have a DescendantInvalidationSet with
//   wholeSubtreeInvalid.
//
// .u ~ * {}
//   For class u we will have a SiblingInvalidationSet with wholeSubtreeInvalid
//   and invalidatesSelf (for all siblings, the sibling itself is invalidated).
//
// .t .v, .t ~ .z {}
//   For class t we will have a SiblingInvalidationSet containing class z, with
//   the SiblingInvalidationSet also holding descendants containing class v.
//
// We avoid virtual functions to minimize space consumption.
class CORE_EXPORT InvalidationSet {
  WTF_MAKE_NONCOPYABLE(InvalidationSet);
  USING_FAST_MALLOC_WITH_TYPE_NAME(blink::InvalidationSet);

 public:
  InvalidationType type() const {
    return static_cast<InvalidationType>(m_type);
  }
  bool isDescendantInvalidationSet() const {
    return type() == InvalidateDescendants;
  }
  bool isSiblingInvalidationSet() const { return type() == InvalidateSiblings; }

  static void cacheTracingFlag();

  bool invalidatesElement(Element&) const;

  void addClass(const AtomicString& className);
  void addId(const AtomicString& id);
  void addTagName(const AtomicString& tagName);
  void addAttribute(const AtomicString& attributeLocalName);

  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; }

  void setInvalidatesSlotted() { m_invalidatesSlotted = true; }
  bool invalidatesSlotted() const { return m_invalidatesSlotted; }

  bool isEmpty() const {
    return !m_classes && !m_ids && !m_tagNames && !m_attributes &&
           !m_customPseudoInvalid && !m_insertionPointCrossing &&
           !m_invalidatesSlotted;
  }

  bool isAlive() const { return m_isAlive; }

  void toTracedValue(TracedValue*) const;

#ifndef NDEBUG
  void show() const;
#endif

  const HashSet<AtomicString>& classSetForTesting() const {
    DCHECK(m_classes);
    return *m_classes;
  }
  const HashSet<AtomicString>& idSetForTesting() const {
    DCHECK(m_ids);
    return *m_ids;
  }
  const HashSet<AtomicString>& tagNameSetForTesting() const {
    DCHECK(m_tagNames);
    return *m_tagNames;
  }
  const HashSet<AtomicString>& attributeSetForTesting() const {
    DCHECK(m_attributes);
    return *m_attributes;
  }

  void ref() { ++m_refCount; }
  void deref() {
    DCHECK_GT(m_refCount, 0);
    --m_refCount;
    if (!m_refCount)
      destroy();
  }

  void combine(const InvalidationSet& other);

 protected:
  explicit InvalidationSet(InvalidationType);

  ~InvalidationSet() {
    RELEASE_ASSERT(m_isAlive);
    m_isAlive = false;
  }

 private:
  void destroy();

  HashSet<AtomicString>& ensureClassSet();
  HashSet<AtomicString>& ensureIdSet();
  HashSet<AtomicString>& ensureTagNameSet();
  HashSet<AtomicString>& ensureAttributeSet();

  // Implement reference counting manually so we can call a derived
  // class destructor when the reference count decreases to 0.
  // If we use RefCounted instead, at least one of our compilers
  // requires the ability for RefCounted<InvalidationSet>::deref()
  // to call ~InvalidationSet(), but this is not a virtual call.
  int m_refCount;

  // FIXME: optimize this if it becomes a memory issue.
  std::unique_ptr<HashSet<AtomicString>> m_classes;
  std::unique_ptr<HashSet<AtomicString>> m_ids;
  std::unique_ptr<HashSet<AtomicString>> m_tagNames;
  std::unique_ptr<HashSet<AtomicString>> m_attributes;

  unsigned m_type : 1;

  // If true, all descendants might be invalidated, so a full subtree recalc is
  // required.
  unsigned m_allDescendantsMightBeInvalid : 1;

  // If true, the element or sibling itself is invalid.
  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;

  // If true, distributed nodes of <slot> elements need to be invalidated.
  unsigned m_invalidatesSlotted : 1;

  // If true, the instance is alive and can be used.
  unsigned m_isAlive : 1;
};

class CORE_EXPORT DescendantInvalidationSet final : public InvalidationSet {
 public:
  static PassRefPtr<DescendantInvalidationSet> create() {
    return adoptRef(new DescendantInvalidationSet);
  }

 private:
  DescendantInvalidationSet() : InvalidationSet(InvalidateDescendants) {}
};

class CORE_EXPORT SiblingInvalidationSet final : public InvalidationSet {
 public:
  static PassRefPtr<SiblingInvalidationSet> create(
      PassRefPtr<DescendantInvalidationSet> descendants) {
    return adoptRef(new SiblingInvalidationSet(std::move(descendants)));
  }

  unsigned maxDirectAdjacentSelectors() const {
    return m_maxDirectAdjacentSelectors;
  }
  void updateMaxDirectAdjacentSelectors(unsigned value) {
    m_maxDirectAdjacentSelectors =
        std::max(value, m_maxDirectAdjacentSelectors);
  }

  DescendantInvalidationSet* siblingDescendants() const {
    return m_siblingDescendantInvalidationSet.get();
  }
  DescendantInvalidationSet& ensureSiblingDescendants();

  DescendantInvalidationSet* descendants() const {
    return m_descendantInvalidationSet.get();
  }
  DescendantInvalidationSet& ensureDescendants();

 private:
  explicit SiblingInvalidationSet(
      PassRefPtr<DescendantInvalidationSet> descendants);

  // Indicates the maximum possible number of siblings affected.
  unsigned m_maxDirectAdjacentSelectors;

  // Indicates the descendants of siblings.
  RefPtr<DescendantInvalidationSet> m_siblingDescendantInvalidationSet;

  // Null if a given feature (class, attribute, id, pseudo-class) has only
  // a SiblingInvalidationSet and not also a DescendantInvalidationSet.
  RefPtr<DescendantInvalidationSet> m_descendantInvalidationSet;
};

using InvalidationSetVector = Vector<RefPtr<InvalidationSet>>;

struct InvalidationLists {
  InvalidationSetVector descendants;
  InvalidationSetVector siblings;
};

DEFINE_TYPE_CASTS(DescendantInvalidationSet,
                  InvalidationSet,
                  value,
                  value->isDescendantInvalidationSet(),
                  value.isDescendantInvalidationSet());
DEFINE_TYPE_CASTS(SiblingInvalidationSet,
                  InvalidationSet,
                  value,
                  value->isSiblingInvalidationSet(),
                  value.isSiblingInvalidationSet());

}  // namespace blink

#endif  // InvalidationSet_h