Source/core/dom/CustomElementCallbackDispatcher.cpp

/*
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#include "config.h"
#include "core/dom/CustomElementCallbackDispatcher.h"

#include "core/dom/CustomElementCallbackInvocation.h"
#include "wtf/MainThread.h"

namespace WebCore {

size_t CustomElementCallbackDispatcher::s_elementQueueStart = 0;

// The base of the stack has a null sentinel value.
size_t CustomElementCallbackDispatcher::s_elementQueueEnd = 1;

CustomElementCallbackDispatcher& CustomElementCallbackDispatcher::instance()
{
    DEFINE_STATIC_LOCAL(CustomElementCallbackDispatcher, instance, ());
    return instance;
}

void CustomElementCallbackDispatcher::enqueueAttributeChangedCallback(PassRefPtr<CustomElementLifecycleCallbacks> callbacks, PassRefPtr<Element> element, const AtomicString& name, const AtomicString& oldValue, const AtomicString& newValue)
{
    if (!callbacks->hasAttributeChangedCallback())
        return;

    CustomElementCallbackQueue* queue = scheduleInCurrentElementQueue(element);
    queue->append(CustomElementCallbackInvocation::createAttributeChangedInvocation(callbacks, name, oldValue, newValue));
}

void CustomElementCallbackDispatcher::enqueueCreatedCallback(PassRefPtr<CustomElementLifecycleCallbacks> callbacks, PassRefPtr<Element> element)
{
    if (!callbacks->hasCreatedCallback())
        return;

    CustomElementCallbackQueue* queue = createCallbackQueue(element);
    queue->setOwner(currentElementQueue());

    // The created callback is unique in being prepended to the front
    // of the element queue
    m_flattenedProcessingStack.insert(inCallbackDeliveryScope() ? s_elementQueueStart : /* skip null sentinel */ 1, queue);
    ++s_elementQueueEnd;

    queue->append(CustomElementCallbackInvocation::createInvocation(callbacks, CustomElementLifecycleCallbacks::Created));
}

void CustomElementCallbackDispatcher::enqueueEnteredDocumentCallback(PassRefPtr<CustomElementLifecycleCallbacks> callbacks, PassRefPtr<Element> element)
{
    if (!callbacks->hasEnteredDocumentCallback())
        return;

    CustomElementCallbackQueue* queue = scheduleInCurrentElementQueue(element);
    queue->append(CustomElementCallbackInvocation::createInvocation(callbacks, CustomElementLifecycleCallbacks::EnteredDocument));
}

void CustomElementCallbackDispatcher::enqueueLeftDocumentCallback(PassRefPtr<CustomElementLifecycleCallbacks> callbacks, PassRefPtr<Element> element)
{
    if (!callbacks->hasLeftDocumentCallback())
        return;

    CustomElementCallbackQueue* queue = scheduleInCurrentElementQueue(element);
    queue->append(CustomElementCallbackInvocation::createInvocation(callbacks, CustomElementLifecycleCallbacks::LeftDocument));
}

// Dispatches callbacks at microtask checkpoint.
bool CustomElementCallbackDispatcher::dispatch()
{
    ASSERT(isMainThread());
    if (inCallbackDeliveryScope())
        return false;

    size_t start = 1; // skip null sentinel
    size_t end = s_elementQueueEnd;

    for (size_t i = start; i < end; i++) {
        m_flattenedProcessingStack[i]->processInElementQueue(currentElementQueue());

        // new callbacks as a result of recursion must be scheduled in
        // a CallbackDeliveryScope which restore this queue on completion
        ASSERT(!s_elementQueueStart);
        ASSERT(s_elementQueueEnd == end);
    }

    s_elementQueueEnd = 1;
    m_flattenedProcessingStack.resize(s_elementQueueEnd);
    m_elementCallbackQueueMap.clear();

    bool didWork = start < end;
    return didWork;
}

// Dispatches callbacks when popping the processing stack.
void CustomElementCallbackDispatcher::processElementQueueAndPop()
{
    instance().processElementQueueAndPop(s_elementQueueStart, s_elementQueueEnd);
}

void CustomElementCallbackDispatcher::processElementQueueAndPop(size_t start, size_t end)
{
    ASSERT(isMainThread());

    for (size_t i = start; i < end; i++) {
        m_flattenedProcessingStack[i]->processInElementQueue(currentElementQueue());

        // process() may run script which grows and shrinks the
        // processing stack above this entry, but the processing stack
        // should always drop back to having this entry at the
        // top-of-stack on exit
        ASSERT(start == s_elementQueueStart);
        ASSERT(end == s_elementQueueEnd);
    }

    // Pop the element queue from the processing stack
    m_flattenedProcessingStack.resize(start);
    s_elementQueueEnd = start;

    if (start == /* allow sentinel */ 1)
        m_elementCallbackQueueMap.clear();
}

CustomElementCallbackQueue* CustomElementCallbackDispatcher::createCallbackQueue(PassRefPtr<Element> element)
{
    Element* key = element.get();
    ElementCallbackQueueMap::AddResult result = m_elementCallbackQueueMap.add(key, CustomElementCallbackQueue::create(element));
    ASSERT(result.isNewEntry);
    return result.iterator->value.get();
}

CustomElementCallbackQueue* CustomElementCallbackDispatcher::ensureCallbackQueue(PassRefPtr<Element> element)
{
    Element* key = element.get();
    ElementCallbackQueueMap::iterator it = m_elementCallbackQueueMap.find(key);
    if (it == m_elementCallbackQueueMap.end())
        it = m_elementCallbackQueueMap.add(key, CustomElementCallbackQueue::create(element)).iterator;
    return it->value.get();
}

// Finds or creates the callback queue for element. If the element's
// callback queue is scheduled in an earlier processing stack frame,
// its owner is set to the element queue on the top of the processing
// stack. Because callback queues are processed exhaustively, this
// effectively moves the callback queue to the top of the stack.
CustomElementCallbackQueue* CustomElementCallbackDispatcher::scheduleInCurrentElementQueue(PassRefPtr<Element> element)
{
    CustomElementCallbackQueue* queue = ensureCallbackQueue(element);
    bool isInCurrentQueue = queue->owner() == currentElementQueue();
    if (!isInCurrentQueue) {
        queue->setOwner(currentElementQueue());
        m_flattenedProcessingStack.append(queue);
        ++s_elementQueueEnd;
    }
    return queue;
}

} // namespace WebCore