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  1. #include <iostream>
  2. #include <vector>
  3.  
  4. class BaseReceiever
  5. {
  6. protected:
  7.  
  8. 	static size_t nextId;
  9. };
  10.  
  11. size_t BaseReceiever::nextId = 0;
  12.  
  13. // if you inherit from this class,
  14. // you are required to implement
  15. // void recieve(const TEventData& eventData)
  16. // where TEventData is an Event (see further down)
  17. template <typename TEventData>
  18. class Receiver
  19. 	: public BaseReceiever
  20. {
  21. public:
  22.  
  23. 	virtual void receive(const TEventData&) = 0;
  24.  
  25. 	static size_t GetId()
  26. 	{ return _id; }
  27.  
  28. private:
  29.  
  30. 	// used for internal storage
  31. 	// identification
  32. 	static size_t _id;
  33. };
  34.  
  35. template<typename T>
  36. size_t Receiver<T>::_id = BaseReceiever::nextId++;
  37.  
  38. struct BaseEvent
  39. {
  40. protected:
  41.  
  42. 	static size_t nextId;
  43. };
  44.  
  45. size_t BaseEvent::nextId = 0;
  46.  
  47. template <typename T>
  48. struct Event
  49. 	: public BaseEvent
  50. {
  51. 	static size_t GetId()
  52. 	{ return _id; }
  53.  
  54. private:
  55.  
  56. 	static size_t _id;
  57. };
  58.  
  59. template <typename T>
  60. size_t Event<T>::_id = BaseEvent::nextId++;
  61.  
  62. class EventHandler
  63. {
  64. 	// note:
  65. 	// could use one vector for better performance
  66. 	// but I doubt it's noticeable
  67.  
  68. 	typedef std::vector<BaseReceiever*> ReceiverArray;
  69. 	typedef std::vector<ReceiverArray> ImplSubscriberArray;
  70.  
  71. public:
  72.  
  73. 	template <typename TEvent>
  74. 	void emit(const TEvent& event)
  75. 	{
  76.         ReceiverArray& receivers = _subscribers[TEvent::GetId()];
  77. 		for(ReceiverArray::iterator i = receivers.begin(); i != receivers.end(); ++i)
  78. 		{
  79. 			static_cast<Receiver<TEvent>&>(*(*i)).receive(event);
  80. 		}
  81. 	}
  82.  
  83. 	template <typename TEvent, typename TReciever>
  84. 	void subscribe(TReciever* receiver)
  85. 	{
  86. 		size_t eventId = TEvent::GetId();
  87. 		size_t receiverId = TReciever::GetId();
  88.  
  89. 		if(_subscribers.size() <= eventId)
  90. 		{
  91. 			_subscribers.resize(eventId + 1);
  92. 		}
  93.  
  94. 		ReceiverArray& receivers = _subscribers[eventId];
  95.  
  96. 		if(receivers.size() <= receiverId)
  97. 		{
  98. 			receivers.resize(receiverId + 1);
  99. 		}
  100.  
  101. 		receivers[receiverId] = receiver;
  102. 	}
  103.  
  104. 	template <typename TEvent, typename TReciever>
  105. 	void unsubscribe(TReciever* reciever)
  106. 	{
  107. 		_subscribers[TEvent::GetId()][TReciever::GetId()] = NULL;
  108. 	}
  109.  
  110. private:
  111.  
  112. 	ImplSubscriberArray _subscribers;
  113. };
  114.  
  115.  
  116. // collision event information
  117. struct Collision
  118. 	: Event<Collision>
  119. {
  120. 	typedef int Entity; // (for this examples sake)
  121.  
  122. 	Collision(Entity E1, Entity E2)
  123. 		: e1(E1),
  124. 	      e2(E2)
  125. 	{
  126. 	}
  127.  
  128. 	Entity e1;
  129. 	Entity e2;
  130. };
  131.  
  132. class MyReciever
  133. 	: public Receiver<Collision>
  134. {
  135. public:
  136.  
  137. 	virtual void receive(const Collision& collision) /*override*/
  138. 	{
  139. 		std::cout << "Collision event occured with " << collision.e1 << " and " << collision.e2 << '\n';
  140. 	}
  141. };
  142.  
  143. int main(int argc, const char * argv[])
  144. {
  145. 	MyReciever collisionReciever;
  146. 	EventHandler handler;
  147.  
  148. 	// subscribe the reciever for events that fire Collision data
  149. 	handler.subscribe<Collision>(&collisionReciever);
  150.  
  151. 	// make a collision object to send
  152. 	Collision collision(5, 4);
  153.  
  154. 	// emit the event
  155. 	handler.emit(collision);
  156.  
  157.     return 0;
  158. }
Success #stdin #stdout 0.01s 2860KB
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Collision event occured with 5 and 4
https://ideone.com/GIa77s
language:
C++ (gcc 8.3)
created:
12 years ago
visibility:
secret

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