Bug 1194112. Part 4 - reimplement Listener/ListenerImpl to support Move. r=kinetik.

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JW Wang 2015-08-18 11:11:53 +08:00
Родитель 5f598a7653
Коммит 1b22c5e8ce
1 изменённых файлов: 124 добавлений и 0 удалений

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@ -190,6 +190,124 @@ private:
Function mFunction; Function mFunction;
}; };
/**
* Define whether an event data should be copied or moved to the listeners.
*
* @Copy Data will always be copied. Each listener gets a copy.
* @Move Data will always be moved.
* @Both Data will be moved when possible or copied when necessary.
*/
enum class EventPassMode : int8_t {
Copy,
Move,
Both
};
class ListenerBase {
public:
ListenerBase() : mToken(new RevocableToken()) {}
~ListenerBase() {
MOZ_ASSERT(Token()->IsRevoked(), "Must disconnect the listener.");
}
RevocableToken* Token() const {
return mToken;
}
private:
const nsRefPtr<RevocableToken> mToken;
};
/**
* Stored by MediaEventSource to send notifications to the listener.
* Since virtual methods can not be templated, this class is specialized
* to provide different Dispatch() overloads depending on EventPassMode.
*/
template <typename ArgType, EventPassMode Mode = EventPassMode::Copy>
class Listener : public ListenerBase {
public:
virtual ~Listener() {}
virtual void Dispatch(const ArgType& aEvent) = 0;
};
template <typename ArgType>
class Listener<ArgType, EventPassMode::Both> : public ListenerBase {
public:
virtual ~Listener() {}
virtual void Dispatch(const ArgType& aEvent) = 0;
virtual void Dispatch(ArgType&& aEvent) = 0;
};
template <typename ArgType>
class Listener<ArgType, EventPassMode::Move> : public ListenerBase {
public:
virtual ~Listener() {}
virtual void Dispatch(ArgType&& aEvent) = 0;
};
/**
* Store the registered target thread and function so it knows where and to
* whom to send the event data.
*/
template <typename Target, typename Function, typename ArgType, EventPassMode>
class ListenerImpl : public Listener<ArgType, EventPassMode::Copy> {
public:
ListenerImpl(Target* aTarget, const Function& aFunction)
: mHelper(ListenerBase::Token(), aTarget, aFunction) {}
void Dispatch(const ArgType& aEvent) override {
mHelper.Dispatch(aEvent);
}
private:
ListenerHelper<Target, Function> mHelper;
};
template <typename Target, typename Function, typename ArgType>
class ListenerImpl<Target, Function, ArgType, EventPassMode::Both>
: public Listener<ArgType, EventPassMode::Both> {
public:
ListenerImpl(Target* aTarget, const Function& aFunction)
: mHelper(ListenerBase::Token(), aTarget, aFunction) {}
void Dispatch(const ArgType& aEvent) override {
mHelper.Dispatch(aEvent);
}
void Dispatch(ArgType&& aEvent) override {
mHelper.Dispatch(Move(aEvent));
}
private:
ListenerHelper<Target, Function> mHelper;
};
template <typename Target, typename Function, typename ArgType>
class ListenerImpl<Target, Function, ArgType, EventPassMode::Move>
: public Listener<ArgType, EventPassMode::Move> {
public:
ListenerImpl(Target* aTarget, const Function& aFunction)
: mHelper(ListenerBase::Token(), aTarget, aFunction) {}
void Dispatch(ArgType&& aEvent) override {
mHelper.Dispatch(Move(aEvent));
}
private:
ListenerHelper<Target, Function> mHelper;
};
/**
* Select EventPassMode based on ListenerMode and if the type is copyable.
*
* @Copy Selected when ListenerMode is NonExclusive because each listener
* must get a copy.
*
* @Move Selected when ListenerMode is Exclusive and the type is move-only.
*
* @Both Selected when ListenerMode is Exclusive and the type is copyable.
* The data will be moved when possible and copied when necessary.
*/
template <typename ArgType, ListenerMode Mode>
struct PassModePicker {
// TODO: pick EventPassMode::Both when we can detect if a type is
// copy-constructible to allow copy-only types in Exclusive mode.
static const EventPassMode Value =
Mode == ListenerMode::NonExclusive ?
EventPassMode::Copy : EventPassMode::Move;
};
} // namespace detail } // namespace detail
template <typename T, ListenerMode> class MediaEventSource; template <typename T, ListenerMode> class MediaEventSource;
@ -239,6 +357,12 @@ template <typename EventType, ListenerMode Mode = ListenerMode::NonExclusive>
class MediaEventSource { class MediaEventSource {
static_assert(!IsReference<EventType>::value, "Ref-type not supported!"); static_assert(!IsReference<EventType>::value, "Ref-type not supported!");
typedef typename detail::EventTypeTraits<EventType>::ArgType ArgType; typedef typename detail::EventTypeTraits<EventType>::ArgType ArgType;
static const detail::EventPassMode PassMode
= detail::PassModePicker<ArgType, Mode>::Value;
typedef detail::Listener<ArgType, PassMode> Listener;
template<typename Target, typename Func>
using ListenerImpl = detail::ListenerImpl<Target, Func, ArgType, PassMode>;
template <typename Method> template <typename Method>
using TakeArgs = detail::TakeArgs<Method>; using TakeArgs = detail::TakeArgs<Method>;