static CounterNode* makeCounterNode(RenderObject* object, const AtomicString& identifier, bool alwaysCreateCounter)
{
    ASSERT(object);

    // Real text nodes don't have their own style so they can't have counters.
    // We can't even look at their styles or we'll see extra resets and increments!
    if (object->isText())
        return nullptr;

    RenderElement* element = toRenderElement(object);

    if (element->hasCounterNodeMap()) {
        if (CounterMap* nodeMap = counterMaps().get(element)) {
            if (CounterNode* node = nodeMap->get(identifier))
                return node;
        }
    }

    bool isReset = false;
    int value = 0;
    if (!planCounter(element, identifier, isReset, value) && !alwaysCreateCounter)
        return nullptr;

    RefPtr<CounterNode> newParent = 0;
    RefPtr<CounterNode> newPreviousSibling = 0;
    RefPtr<CounterNode> newNode = CounterNode::create(element, isReset, value);
    if (findPlaceForCounter(element, identifier, isReset, newParent, newPreviousSibling))
        newParent->insertAfter(newNode.get(), newPreviousSibling.get(), identifier);
    CounterMap* nodeMap;
    if (element->hasCounterNodeMap())
        nodeMap = counterMaps().get(element);
    else {
        nodeMap = new CounterMap;
        counterMaps().set(element, adoptPtr(nodeMap));
        element->setHasCounterNodeMap(true);
    }
    nodeMap->set(identifier, newNode);
    if (newNode->parent())
        return newNode.get();
    // Checking if some nodes that were previously counter tree root nodes
    // should become children of this node now.
    CounterMaps& maps = counterMaps();
    Element* stayWithin = parentOrPseudoHostElement(element);
    bool skipDescendants;
    for (RenderElement* currentRenderer = nextInPreOrder(element, stayWithin); currentRenderer; currentRenderer = nextInPreOrder(currentRenderer, stayWithin, skipDescendants)) {
        skipDescendants = false;
        if (!currentRenderer->hasCounterNodeMap())
            continue;
        CounterNode* currentCounter = maps.get(currentRenderer)->get(identifier);
        if (!currentCounter)
            continue;
        skipDescendants = true;
        if (currentCounter->parent())
            continue;
        if (stayWithin == parentOrPseudoHostElement(currentRenderer) && currentCounter->hasResetType())
            break;
        newNode->insertAfter(currentCounter, newNode->lastChild(), identifier);
    }
    return newNode.get();
}

static CounterNode* makeCounterNode(RenderObject* object, const AtomicString& identifier, bool alwaysCreateCounter)
{
    ASSERT(object);

    if (object->m_hasCounterNodeMap) {
        if (CounterMap* nodeMap = counterMaps().get(object)) {
            if (CounterNode* node = nodeMap->get(identifier.impl()).get())
                return node;
        }
    }

    bool isReset = false;
    int value = 0;
    if (!planCounter(object, identifier, isReset, value) && !alwaysCreateCounter)
        return 0;

    CounterNode* newParent = 0;
    CounterNode* newPreviousSibling = 0;
    RefPtr<CounterNode> newNode = CounterNode::create(object, isReset, value);
    if (findPlaceForCounter(object, identifier, isReset, newParent, newPreviousSibling))
        newParent->insertAfter(newNode.get(), newPreviousSibling, identifier);
    CounterMap* nodeMap;
    if (object->m_hasCounterNodeMap)
        nodeMap = counterMaps().get(object);
    else {
        nodeMap = new CounterMap;
        counterMaps().set(object, nodeMap);
        object->m_hasCounterNodeMap = true;
    }
    nodeMap->set(identifier.impl(), newNode);
    if (newNode->parent())
        return newNode.get();
    // Checking if some nodes that were previously counter tree root nodes
    // should become children of this node now.
    CounterMaps& maps = counterMaps();
    Element* stayWithin = parentElement(object);
    bool skipDescendants;
    for (RenderObject* currentRenderer = nextInPreOrder(object, stayWithin); currentRenderer; currentRenderer = nextInPreOrder(currentRenderer, stayWithin, skipDescendants)) {
        skipDescendants = false;
        if (!currentRenderer->m_hasCounterNodeMap)
            continue;
        CounterNode* currentCounter = maps.get(currentRenderer)->get(identifier.impl()).get();
        if (!currentCounter)
            continue;
        skipDescendants = true;
        if (currentCounter->parent()) {
            ASSERT(newNode->firstChild());
            continue;
        }
        if (stayWithin == parentElement(currentRenderer) && currentCounter->hasResetType())
            break;
        newNode->insertAfter(currentCounter, newNode->lastChild(), identifier);
    }
    return newNode.get();
}

static void destroyCounterNodeWithoutMapRemoval(const AtomicString& identifier, CounterNode* node)
{
    CounterNode* previous;
    for (RefPtr<CounterNode> child = node->lastDescendant(); child && child != node; child = previous) {
        previous = child->previousInPreOrder();
        child->parent()->removeChild(child.get());
        ASSERT(counterMaps().get(child->owner())->get(identifier) == child);
        counterMaps().get(child->owner())->remove(identifier);
    }
    if (CounterNode* parent = node->parent())
        parent->removeChild(node);
}

static CounterNode* makeCounterNode(RenderElement& renderer, const AtomicString& identifier, bool alwaysCreateCounter)
{
    if (renderer.hasCounterNodeMap()) {
        if (CounterMap* nodeMap = counterMaps().get(&renderer)) {
            if (CounterNode* node = nodeMap->get(identifier))
                return node;
        }
    }

    bool isReset = false;
    int value = 0;
    if (!planCounter(renderer, identifier, isReset, value) && !alwaysCreateCounter)
        return nullptr;

    RefPtr<CounterNode> newParent = 0;
    RefPtr<CounterNode> newPreviousSibling = 0;
    RefPtr<CounterNode> newNode = CounterNode::create(renderer, isReset, value);
    if (findPlaceForCounter(renderer, identifier, isReset, newParent, newPreviousSibling))
        newParent->insertAfter(newNode.get(), newPreviousSibling.get(), identifier);
    CounterMap* nodeMap;
    if (renderer.hasCounterNodeMap())
        nodeMap = counterMaps().get(&renderer);
    else {
        nodeMap = new CounterMap;
        counterMaps().set(&renderer, std::unique_ptr<CounterMap>(nodeMap));
        renderer.setHasCounterNodeMap(true);
    }
    nodeMap->set(identifier, newNode);
    if (newNode->parent())
        return newNode.get();
    // Checking if some nodes that were previously counter tree root nodes
    // should become children of this node now.
    CounterMaps& maps = counterMaps();
    Element* stayWithin = parentOrPseudoHostElement(renderer);
    bool skipDescendants;
    for (RenderElement* currentRenderer = nextInPreOrder(renderer, stayWithin); currentRenderer; currentRenderer = nextInPreOrder(*currentRenderer, stayWithin, skipDescendants)) {
        skipDescendants = false;
        if (!currentRenderer->hasCounterNodeMap())
            continue;
        CounterNode* currentCounter = maps.get(currentRenderer)->get(identifier);
        if (!currentCounter)
            continue;
        skipDescendants = true;
        if (currentCounter->parent())
            continue;
        if (stayWithin == parentOrPseudoHostElement(*currentRenderer) && currentCounter->hasResetType())
            break;
        newNode->insertAfter(currentCounter, newNode->lastChild(), identifier);
    }
    return newNode.get();
}

static void updateCounters(RenderObject* renderer)
{
    ASSERT(renderer->style());
    const CounterDirectiveMap* directiveMap = renderer->style()->counterDirectives();
    if (!directiveMap)
        return;
    CounterDirectiveMap::const_iterator end = directiveMap->end();
    if (!renderer->hasCounterNodeMap()) {
        for (CounterDirectiveMap::const_iterator it = directiveMap->begin(); it != end; ++it)
            makeCounterNode(renderer, it->key, false);
        return;
    }
    CounterMap* counterMap = counterMaps().get(renderer);
    ASSERT(counterMap);
    for (CounterDirectiveMap::const_iterator it = directiveMap->begin(); it != end; ++it) {
        RefPtr<CounterNode> node = counterMap->get(it->key);
        if (!node) {
            makeCounterNode(renderer, it->key, false);
            continue;
        }
        RefPtr<CounterNode> newParent = 0;
        RefPtr<CounterNode> newPreviousSibling = 0;
        
        findPlaceForCounter(renderer, it->key, node->hasResetType(), newParent, newPreviousSibling);
        if (node != counterMap->get(it->key))
            continue;
        CounterNode* parent = node->parent();
        if (newParent == parent && newPreviousSibling == node->previousSibling())
            continue;
        if (parent)
            parent->removeChild(node.get());
        if (newParent)
            newParent->insertAfter(node.get(), newPreviousSibling.get(), it->key);
    }
}

static void destroyCounterNodeChildren(AtomicStringImpl* identifier, CounterNode* node)
{
    CounterNode* previous;
    for (CounterNode* child = lastDescendant(node); child && child != node; child = previous) {
        previous = previousInPreOrder(child);
        child->parent()->removeChild(child);
        ASSERT(counterMaps().get(child->renderer())->get(identifier) == child);
        counterMaps().get(child->renderer())->remove(identifier);
        if (!child->renderer()->documentBeingDestroyed()) {
            RenderObjectChildList* children = child->renderer()->virtualChildren();
            if (children)
                children->invalidateCounters(child->renderer());
        }
        delete child;
    }
}

void RenderCounter::destroyCounterNodes(RenderObject* owner)
{
    CounterMaps& maps = counterMaps();
    CounterMaps::iterator mapsIterator = maps.find(owner);
    if (mapsIterator == maps.end())
        return;
    CounterMap* map = mapsIterator->value.get();
    CounterMap::const_iterator end = map->end();
    for (CounterMap::const_iterator it = map->begin(); it != end; ++it) {
        destroyCounterNodeWithoutMapRemoval(it->key, it->value.get());
    }
    maps.remove(mapsIterator);
    owner->setHasCounterNodeMap(false);
}

static CounterNode* counter(RenderObject* object, const AtomicString& counterName, bool alwaysCreateCounter)
{
    ASSERT(object);

    if (object->m_hasCounterNodeMap)
        if (CounterMap* nodeMap = counterMaps().get(object))
            if (CounterNode* node = nodeMap->get(counterName.impl()))
                return node;

    bool isReset = false;
    int value = 0;
    if (!planCounter(object, counterName, isReset, value) && !alwaysCreateCounter)
        return 0;

    CounterNode* newParent = 0;
    CounterNode* newPreviousSibling = 0;
    CounterNode* newNode;
    if (findPlaceForCounter(object, counterName, isReset, newParent, newPreviousSibling)) {
        newNode = new CounterNode(object, isReset, value);
        newParent->insertAfter(newNode, newPreviousSibling);
    } else {
        // Make a reset node for counters that aren't inside an existing reset node.
        newNode = new CounterNode(object, true, value);
    }

    CounterMap* nodeMap;
    if (object->m_hasCounterNodeMap)
        nodeMap = counterMaps().get(object);
    else {
        nodeMap = new CounterMap;
        counterMaps().set(object, nodeMap);
        object->m_hasCounterNodeMap = true;
    }
    nodeMap->set(counterName.impl(), newNode);

    return newNode;
}

void RenderCounter::destroyCounterNodes(RenderObject* object)
{
    CounterMaps& maps = counterMaps();
    CounterMap* map = maps.get(object);
    if (!map)
        return;
    maps.remove(object);

    CounterMap::const_iterator end = map->end();
    for (CounterMap::const_iterator it = map->begin(); it != end; ++it) {
        CounterNode* node = it->second;
        destroyCounterNodeChildren(it->first.get(), node);
        if (CounterNode* parent = node->parent())
            parent->removeChild(node);
        delete node;
    }

    delete map;
}