C++ (Cpp) Cache::lookup示例

inline bool
nsNthIndexCache::IndexDeterminedFromPreviousSibling(nsIContent* aSibling,
                                                    Element* aChild,
                                                    bool aIsOfType,
                                                    bool aIsFromEnd,
                                                    const Cache& aCache,
                                                    int32_t& aResult)
{
  if (SiblingMatchesElement(aSibling, aChild, aIsOfType)) {
    Cache::Ptr siblingEntry = aCache.lookup(aSibling);
    if (siblingEntry) {
      int32_t siblingIndex = siblingEntry->value;
      NS_ASSERTION(siblingIndex != 0,
                   "How can a non-anonymous node have an anonymous sibling?");
      if (siblingIndex > 0) {
        // At this point, aResult is a count of how many elements matching
        // aChild we have seen after aSibling, including aChild itself.
        // |siblingIndex| is the index of aSibling.
        // So if aIsFromEnd, we want |aResult = siblingIndex - aResult| and
        // otherwise we want |aResult = siblingIndex + aResult|.
        NS_ABORT_IF_FALSE(aIsFromEnd == 0 || aIsFromEnd == 1,
                          "Bogus bool value");
        aResult = siblingIndex + aResult * (1 - 2 * aIsFromEnd);
        return true;
      }
    }
    
    ++aResult;
  }

  return false;
}