Source/core/dom/CustomElementCallbackDispatcher.cpp

/*
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 *    may be used to endorse or promote products derived from this
 *    software without specific prior written permission.
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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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 = kNumSentinels;

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

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

    size_t start = kNumSentinels; // skip null sentinel
    size_t end = s_elementQueueEnd;
    ElementQueue thisQueue = currentElementQueue();

    for (size_t i = start; i < end; i++) {
        {
            // The created callback may schedule entered document
            // callbacks.
            CallbackDeliveryScope deliveryScope;
            m_flattenedProcessingStack[i]->processInElementQueue(thisQueue);
        }

        ASSERT(!s_elementQueueStart);
        ASSERT(s_elementQueueEnd == end);
    }

    s_elementQueueEnd = kNumSentinels;
    m_flattenedProcessingStack.resize(s_elementQueueEnd);

    ElementCallbackQueueMap emptyMap;
    m_elementCallbackQueueMap.swap(emptyMap);

    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());
    ElementQueue thisQueue = currentElementQueue();

    for (size_t i = start; i < end; i++) {
        {
            // The created callback may schedule entered document
            // callbacks.
            CallbackDeliveryScope deliveryScope;
            m_flattenedProcessingStack[i]->processInElementQueue(thisQueue);
        }

        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 == kNumSentinels) {
        ElementCallbackQueueMap emptyMap;
        m_elementCallbackQueueMap.swap(emptyMap);
    }
}

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
// createdCallback has not finished running, the callback queue is not
// moved to the top-of-stack. Otherwise like
// scheduleInCurrentElementQueue.
CustomElementCallbackQueue* CustomElementCallbackDispatcher::schedule(PassRefPtr<Element> element)
{
    CustomElementCallbackQueue* callbackQueue = ensureCallbackQueue(element);
    if (!callbackQueue->inCreatedCallback())
        ensureInCurrentElementQueue(callbackQueue);
    return callbackQueue;
}

// 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* callbackQueue = ensureCallbackQueue(element);
    ensureInCurrentElementQueue(callbackQueue);
    return callbackQueue;
}

void CustomElementCallbackDispatcher::ensureInCurrentElementQueue(CustomElementCallbackQueue* callbackQueue)
{
    if (callbackQueue->owner() == currentElementQueue())
        return;

    callbackQueue->setOwner(currentElementQueue());
    m_flattenedProcessingStack.append(callbackQueue);
    ++s_elementQueueEnd;
}

} // namespace WebCore