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

/*
 * Copyright (C) 2013 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
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#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/Vector.h"
#include "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() {}

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

  void watchCSSSelectors(const Vector<String>& selectors);
  const HeapVector<Member<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(TimerBase*);
  Document& document() const { return *m_document; }

  Member<Document> m_document;

  HeapVector<Member<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