third_party/WebKit/Source/core/dom/shadow/SelectRuleFeatureSet.cpp

/*
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#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