text: /*
   * Copyright (C) 2012 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.
   */
  
  #include "core/dom/shadow/SelectRuleFeatureSet.h"
  
  #include "core/css/CSSSelector.h"
  #include "core/css/CSSSelectorList.h"
  
  #include "wtf/BitVector.h"
  
  namespace blink {
  
  void SelectRuleFeatureSet::collectFeaturesFromSelectorList(
      const CSSSelectorList& list) {
    for (const CSSSelector* selector = list.first(); selector;
         selector = CSSSelectorList::next(*selector)) {
      for (const CSSSelector* component = selector; component;
           component = component->tagHistory()) {
        if (invalidationSetForSimpleSelector(*component, InvalidateDescendants))
          continue;
  
        if (component->selectorList())
          collectFeaturesFromSelectorList(*component->selectorList());
      }
    }
  }
  
  bool SelectRuleFeatureSet::checkSelectorsForClassChange(
      const SpaceSplitString& changedClasses) const {
    unsigned changedSize = changedClasses.size();
    for (unsigned i = 0; i < changedSize; ++i) {
      if (hasSelectorForClass(changedClasses[i]))
        return true;
    }
    return false;
  }
  
  bool SelectRuleFeatureSet::checkSelectorsForClassChange(
      const SpaceSplitString& oldClasses,
      const SpaceSplitString& newClasses) const {
    if (!oldClasses.size())
      return checkSelectorsForClassChange(newClasses);
  
    // Class vectors tend to be very short. This is faster than using a hash
    // table.
    BitVector remainingClassBits;
    remainingClassBits.ensureSize(oldClasses.size());
  
    for (unsigned i = 0; i < newClasses.size(); ++i) {
      bool found = false;
      for (unsigned j = 0; j < oldClasses.size(); ++j) {
        if (newClasses[i] == oldClasses[j]) {
          // Mark each class that is still in the newClasses so we can skip doing
          // an n^2 search below when looking for removals. We can't break from
          // this loop early since a class can appear more than once.
          remainingClassBits.quickSet(j);
          found = true;
        }
      }
      // Class was added.
      if (!found) {
        if (hasSelectorForClass(newClasses[i]))
          return true;
      }
    }
  
    for (unsigned i = 0; i < oldClasses.size(); ++i) {
      if (remainingClassBits.quickGet(i))
        continue;
  
      // Class was removed.
      if (hasSelectorForClass(oldClasses[i]))
        return true;
    }
    return false;
  }
  
  }  // namespace blink
  