Source/core/dom/CSSSelectorWatch.h

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#ifndef CSSSelectorWatch_h
#define CSSSelectorWatch_h

#include "core/css/StyleRule.h"
#include "core/dom/DocumentSupplementable.h"
#include "platform/Timer.h"
#include "wtf/HashSet.h"
#include "wtf/RefPtr.h"
#include "wtf/Vector.h"
#include "wtf/WeakPtr.h"
#include "wtf/text/WTFString.h"

namespace WebCore {

class CSSSelectorWatch : public DocumentSupplement {
public:
    virtual ~CSSSelectorWatch() { }

    static CSSSelectorWatch& from(Document&);

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

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

private:
    CSSSelectorWatch(Document&);
    void callbackSelectorChangeTimerFired(Timer<CSSSelectorWatch>*);

    Document& m_document;

    Vector<RefPtr<StyleRule> > m_watchedCallbackSelectors;

    // Maps a CSS selector string with a -webkit-callback property to the number
    // of matching RenderStyle objects in this document.
    HashMap<String, int> 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;
};

} // namespace WebCore

#endif // CSSSelectorWatch_h