third_party/WebKit/Source/core/css/CSSSelectorWatch.h

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#ifndef CSSSelectorWatch_h
#define CSSSelectorWatch_h

#include "core/CoreExport.h"
#include "core/css/StyleRule.h"
#include "core/dom/Document.h"
#include "platform/Timer.h"
#include "platform/wtf/HashCountedSet.h"
#include "platform/wtf/HashSet.h"
#include "platform/wtf/Vector.h"
#include "platform/wtf/text/WTFString.h"

namespace blink {

class CORE_EXPORT CSSSelectorWatch final
    : public GarbageCollectedFinalized<CSSSelectorWatch>,
      public Supplement<Document> {
  USING_GARBAGE_COLLECTED_MIXIN(CSSSelectorWatch);

 public:
  virtual ~CSSSelectorWatch() = default;

  static CSSSelectorWatch& From(Document&);
  static CSSSelectorWatch* FromIfExists(Document&);

  void WatchCSSSelectors(const Vector<String>& selectors);
  const HeapVector<Member<StyleRule>>& WatchedCallbackSelectors() const {
    return watched_callback_selectors_;
  }

  void UpdateSelectorMatches(const Vector<String>& removed_selectors,
                             const Vector<String>& added_selectors);

  virtual void Trace(blink::Visitor*);

 private:
  explicit CSSSelectorWatch(Document&);
  void CallbackSelectorChangeTimerFired(TimerBase*);

  HeapVector<Member<StyleRule>> watched_callback_selectors_;

  // Maps a CSS selector string with a -webkit-callback property to the number
  // of matching ComputedStyle objects in this document.
  HashCountedSet<String> matching_callback_selectors_;
  // Selectors are relative to m_matchingCallbackSelectors's contents at
  // the previous call to selectorMatchChanged.
  HashSet<String> added_selectors_;
  HashSet<String> removed_selectors_;

  TaskRunnerTimer<CSSSelectorWatch> callback_selector_change_timer_;

  // When an element is reparented, the new location's style is evaluated after
  // the expriation of the relayout timer.  We don't want to send redundant
  // callbacks to the embedder, so this counter lets us wait another time around
  // the event loop.
  int timer_expirations_;

  friend class CSSSelectorWatchTest;
};

}  // namespace blink

#endif  // CSSSelectorWatch_h