#include <list>
#include <functional>


namespace CXXHelper
{

	template <typename... Args>
	class Event
	{
	protected:
		std::list <std::function <void (Args...)> > m_handlers;

	public:
		Event () { }
		Event (Event && from)
		{
			m_handlers.swap (from.m_handlers);
		}

		Event (const Event & from)
		{
			from.CopyTo (*this);
		}

		Event & operator = (const Event & from)
		{
			from.CopyTo (*this);
			return (*this);
		}

		Event & operator = (Event && from)
		{
			m_handlers.swap (from.m_handlers);
			return (*this);
		}

		void swap (Event & from)
		{
			m_handlers.swap (from.m_handlers);
		}

		void CopyTo (Event & to) const
		{
			to.m_handlers = m_handlers;
		}

		void Release ()
		{
			m_handlers.clear ();
		}

		virtual ~Event () { }

	public:
		inline void operator () (Args... arg)
		{
			Invoke (arg...);
		}

		inline void Invoke (Args... arg)
		{
			for (auto & h : m_handlers)
				h (arg...);
		}


	public:
		inline void RemoveAll ()
		{
			Release ();
		}

		inline bool IsEmpty () const
		{
			return m_handlers.empty ();
		}

		inline int  GetSize () const
		{
			return (int)m_handlers.size ();
		}

		inline void AppendFrom (const Event & from)
		{
			for (auto h : from.m_handlers)
				this->m_handlers.push_back (h);
		}

	public:
		Event & operator += (Event & from)
		{
			AppendFrom (from);
			return (*this);
		}

	public:
		template <typename TA>
		Event & operator += (TA v)
		{
			Push (v);
			return (*this);
		}

	public:
		//	lambda 表达式会到这里
		//	Binder (bind 结果) 会到这里
		template <typename TX>
		//	inline void Push (const TX & handler)
		inline void Push (TX handler)
		{
			m_handlers.push_back (std::move (handler));
		}

		//	静态函数会到这里
		inline void Push (void (*fn) (Args...))
		{
			m_handlers.push_back (std::move (fn));
		}


		//	类的成员函数会到这里 - 3 个
		//	这里用了个小技巧: 把类实例和成员函数转换成一个临时的 lambda 函数
		template <typename TC>
		inline void Push (TC * inst, void (TC::* mfn) (Args...))
		{
			m_handlers.push_back ([inst, mfn] (Args... args) {(*inst.*mfn) (args...); });
		}

		template <typename TC>
		void Push (TC * inst, void (TC::* mfn) (Args...) const)
		{
			m_handlers.push_back ([inst, mfn] (Args... args) {(*inst.*mfn) (args...); });
		}

		template<typename TC>
		void Push (const TC * inst, void (TC::* mfn) (Args...) const)
		{
			m_handlers.push_back ([inst, mfn] (Args... args) {(*inst.*mfn) (args...); });
		}
	};


}