void HTMLFormattingElementList::tryToEnsureNoahsArkConditionQuickly(
HTMLStackItem* newItem,
HeapVector<Member<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.
HeapVector<Member<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();
if (newItem->localName() != candidate->localName() ||
newItem->namespaceURI() != candidate->namespaceURI())
continue;
if (candidate->attributes().size() != newItemAttributeCount)
continue;
candidates.append(candidate);
}
// There's room for the new element in the ark. There's no need to copy out
// the remainingCandidates.
if (candidates.size() < kNoahsArkCapacity)
return;
remainingCandidates.appendVector(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());
}
