event.hpp

An article on the implementation of a fast C++ delegate with many advanced features.

/*
	(c) Sergey Ryazanov (http://home.onego.ru/~ryazanov)

	Fast delegate compatible with C++ Standard.
*/
#ifndef SRUTIL_EVENT_INCLUDED
#define SRUTIL_EVENT_INCLUDED

namespace srutil
{
	template <typename TSink> class event_source;
	template <typename TSink> class event_binder;

	template <typename TSink> class event_binder
	{
	public:
		typedef TSink sink_type;
		typedef event_source<sink_type> event_source_type;

		event_binder() : sink(sink_type()) {next = prev = this;}
		~event_binder() {unbind();}

		void bind(const event_source<sink_type>& source, sink_type sink);
		void unbind()
		{
			prev->next = next;
			next->prev = prev;
			next = prev = this;
		}

	private:		
		event_binder* prev;
		event_binder* next;
		sink_type sink;
		friend class event_source<sink_type>;

		void attach_after(event_binder* that)
		{
			next = that->next;
			next->prev = this;
			that->next = this;
			prev = that;
		}

		event_binder(event_binder const&);
		event_binder const& operator=(event_binder const&);
	};

	template <typename TSink> class event_source
	{
	public:
		typedef TSink sink_type;
		typedef event_binder<sink_type> binder_type;

		void bind(binder_type& bndr, sink_type sink)
		{
			bndr.attach_after(&list_head);
			bndr.sink = sink;
		}

		template <class TInvoker>
		void emit(TInvoker const& invoker)
		{
			binder_type* current = list_head.next;
			while (current != &list_head)
			{
				if (current->sink)
				{
					event_binder<sink_type> bookmark;
					bookmark.attach_after(current);
					invoker(current->sink); // *current may be excluded from list, but mookmark will always keep valid
					current = bookmark.next;
				}
				else
					current = current->next;
			}
		}

	private:
		mutable binder_type list_head;
		friend class event_binder<sink_type>;
	};

	template <typename TSink>
	void event_binder<TSink>::bind(const event_source<sink_type>& source, sink_type sink)
	{
		unbind();

		attach_after(&source.list_head);
		this->sink = sink;
	}
}
#endif// SRUTIL_EVENT_INCLUDED