third_party/WebKit/Source/core/dom/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 "wtf/HashCountedSet.h"
#include "wtf/HashSet.h"
#include "wtf/RefPtr.h"
#include "wtf/Vector.h"
#include "wtf/text/WTFString.h"

namespace blink {

class CORE_EXPORT CSSSelectorWatch final : public NoBaseWillBeGarbageCollectedFinalized<CSSSelectorWatch>, public WillBeHeapSupplement<Document> {
    WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(CSSSelectorWatch);
    USING_FAST_MALLOC_WILL_BE_REMOVED(CSSSelectorWatch);
public:
    virtual ~CSSSelectorWatch() { }

    static CSSSelectorWatch& from(Document&);
    static CSSSelectorWatch* fromIfExists(Document&);

    void watchCSSSelectors(const Vector<String>& selectors);
    const WillBeHeapVector<RefPtrWillBeMember<StyleRule>>& watchedCallbackSelectors() const { return m_watchedCallbackSelectors; }

    void updateSelectorMatches(const Vector<String>& removedSelectors, const Vector<String>& addedSelectors);

    DECLARE_VIRTUAL_TRACE();

private:
    explicit CSSSelectorWatch(Document&);
    void callbackSelectorChangeTimerFired(Timer<CSSSelectorWatch>*);
    Document& document() const { return *m_document; }

    RawPtrWillBeMember<Document> m_document;

    WillBeHeapVector<RefPtrWillBeMember<StyleRule>> m_watchedCallbackSelectors;

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

    Timer<CSSSelectorWatch> m_callbackSelectorChangeTimer;

    // 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 m_timerExpirations;

    friend class CSSSelectorWatchTest;
};

} // namespace blink

#endif // CSSSelectorWatch_h