util/events.lua

-- Prosody IM

-- Copyright (C) 2008-2010 Matthew Wild

-- Copyright (C) 2008-2010 Waqas Hussain

-- 

-- This project is MIT/X11 licensed. Please see the

-- COPYING file in the source package for more information.

--

local pairs = pairs;

local t_insert = table.insert;

local t_sort = table.sort;

local setmetatable = setmetatable;

local next = next;

module "events"

function new()

	local handlers = {};

	local event_map = {};

	local function _rebuild_index(handlers, event)

		local _handlers = event_map[event];

		if not _handlers or next(_handlers) == nil then return; end

		local index = {};

		for handler in pairs(_handlers) do

			t_insert(index, handler);

		end

		t_sort(index, function(a, b) return _handlers[a] > _handlers[b]; end);

		handlers[event] = index;

		return index;

	end;

	setmetatable(handlers, { __index = _rebuild_index });

	local function add_handler(event, handler, priority)

		local map = event_map[event];

		if map then

			map[handler] = priority or 0;

		else

			map = {[handler] = priority or 0};

			event_map[event] = map;

		end

		handlers[event] = nil;

	end;

	local function remove_handler(event, handler)

		local map = event_map[event];

		if map then

			map[handler] = nil;

			handlers[event] = nil;

			if next(map) == nil then

				event_map[event] = nil;

			end

		end

	end;

	local function add_handlers(handlers)

		for event, handler in pairs(handlers) do

			add_handler(event, handler);

		end

	end;

	local function remove_handlers(handlers)

		for event, handler in pairs(handlers) do

			remove_handler(event, handler);

		end

	end;

	local function fire_event(event, ...)

		local h = handlers[event];

		if h then

			for i=1,#h do

				local ret = h[i](...);

				if ret ~= nil then return ret; end

			end

		end

	end;

	return {

		add_handler = add_handler;

		remove_handler = remove_handler;

		add_handlers = add_handlers;

		remove_handlers = remove_handlers;

		fire_event = fire_event;

		_handlers = handlers;

		_event_map = event_map;

	};

end

return _M;