void HTMLFormattingElementList::tryToEnsureNoahsArkConditionQuickly(HTMLStackItem* newItem, Vector<HTMLStackItem*>& remainingCandidates) { ASSERT(remainingCandidates.isEmpty()); if (m_entries.size() < kNoahsArkCapacity) return; // Use a vector with inline capacity to avoid a malloc in the common case // of a quickly ensuring the condition. Vector<HTMLStackItem*, 10> candidates; size_t newItemAttributeCount = newItem->attributes().size(); for (size_t i = m_entries.size(); i; ) { --i; Entry& entry = m_entries[i]; if (entry.isMarker()) break; // Quickly reject obviously non-matching candidates. HTMLStackItem* candidate = entry.stackItem().get(); if (newItem->localName() != candidate->localName() || newItem->namespaceURI() != candidate->namespaceURI()) continue; if (candidate->attributes().size() != newItemAttributeCount) continue; candidates.append(candidate); } if (candidates.size() < kNoahsArkCapacity) return; // There's room for the new element in the ark. There's no need to copy out the remainingCandidates. remainingCandidates.append(candidates); }
void HTMLFormattingElementList::ensureNoahsArkCondition(HTMLStackItem* newItem) { Vector<HTMLStackItem*> candidates; tryToEnsureNoahsArkConditionQuickly(newItem, candidates); if (candidates.isEmpty()) return; // We pre-allocate and re-use this second vector to save one malloc per // attribute that we verify. Vector<HTMLStackItem*> remainingCandidates; remainingCandidates.reserveInitialCapacity(candidates.size()); const Vector<Attribute>& attributes = newItem->attributes(); for (size_t i = 0; i < attributes.size(); ++i) { const Attribute& attribute = attributes[i]; for (size_t j = 0; j < candidates.size(); ++j) { HTMLStackItem* candidate = candidates[j]; // These properties should already have been checked by tryToEnsureNoahsArkConditionQuickly. ASSERT(newItem->attributes().size() == candidate->attributes().size()); ASSERT(newItem->localName() == candidate->localName() && newItem->namespaceURI() == candidate->namespaceURI()); Attribute* candidateAttribute = candidate->getAttributeItem(attribute.name()); if (candidateAttribute && candidateAttribute->value() == attribute.value()) remainingCandidates.append(candidate); } if (remainingCandidates.size() < kNoahsArkCapacity) return; candidates.swap(remainingCandidates); remainingCandidates.shrink(0); } // Inductively, we shouldn't spin this loop very many times. It's possible, // however, that we wil spin the loop more than once because of how the // formatting element list gets permuted. for (size_t i = kNoahsArkCapacity - 1; i < candidates.size(); ++i) remove(candidates[i]->element()); }