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* Copyright (C) 2013 Google Inc. All rights reserved.
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*
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* may be used to endorse or promote products derived from this
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*
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#ifndef CustomElementCallbackDispatcher_h
#define CustomElementCallbackDispatcher_h
#include "core/dom/custom/CustomElementCallbackQueue.h"
#include "wtf/Vector.h"
namespace WebCore {
class CustomElementScheduler;
// FIXME: Rename this CustomElementProcessingStack. It only handles
// the processing stack.
class CustomElementCallbackDispatcher {
WTF_MAKE_NONCOPYABLE(CustomElementCallbackDispatcher);
public:
// This is stack allocated in many DOM callbacks. Make it cheap.
class CallbackDeliveryScope {
public:
CallbackDeliveryScope()
: m_savedElementQueueStart(s_elementQueueStart)
{
s_elementQueueStart = s_elementQueueEnd;
}
~CallbackDeliveryScope()
{
if (s_elementQueueStart != s_elementQueueEnd)
processElementQueueAndPop();
s_elementQueueStart = m_savedElementQueueStart;
}
private:
size_t m_savedElementQueueStart;
};
static bool inCallbackDeliveryScope() { return s_elementQueueStart; }
protected:
friend class CustomElementScheduler;
static CustomElementCallbackDispatcher& instance();
void enqueue(CustomElementCallbackQueue*);
private:
CustomElementCallbackDispatcher()
{
// Add a null element as a sentinel. This makes it possible to
// identify elements queued when there is no
// CallbackDeliveryScope active. Also, if the processing stack
// is popped when empty, this sentinel will cause a null deref
// crash.
CustomElementCallbackQueue* sentinel = 0;
for (size_t i = 0; i < kNumSentinels; i++)
m_flattenedProcessingStack.append(sentinel);
ASSERT(s_elementQueueEnd == m_flattenedProcessingStack.size());
}
// The start of the element queue on the top of the processing
// stack. An offset into instance().m_flattenedProcessingStack.
static size_t s_elementQueueStart;
// The end of the element queue on the top of the processing
// stack. A cache of instance().m_flattenedProcessingStack.size().
static size_t s_elementQueueEnd;
static CustomElementCallbackQueue::ElementQueueId currentElementQueue() { return CustomElementCallbackQueue::ElementQueueId(s_elementQueueStart); }
static void processElementQueueAndPop();
void processElementQueueAndPop(size_t start, size_t end);
// The processing stack, flattened. Element queues lower in the
// stack appear toward the head of the vector. The first element
// is a null sentinel value.
static const size_t kNumSentinels = 1;
Vector<CustomElementCallbackQueue*> m_flattenedProcessingStack;
};
}
#endif // CustomElementCallbackDispatcher_h