File

util/events.lua @ 12590:5eaf77114fdb

compat: Use table.pack (there since Lua 5.2) over our util.table Added in d278a770eddc avoid having to deal with its absence in Lua 5.1. No longer needed when Lua 5.1 support is dropped.
author Kim Alvefur <zash@zash.se>
date Mon, 11 Jul 2022 19:15:24 +0200
parent 11058:c99afee1c548
line wrap: on
line source

-- 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_remove = table.remove;
local t_sort = table.sort;
local setmetatable = setmetatable;
local next = next;

local _ENV = nil;
-- luacheck: std none

local function new()
	-- Map event name to ordered list of handlers (lazily built): handlers[event_name] = array_of_handler_functions
	local handlers = {};
	-- Array of wrapper functions that wrap all events (nil if empty)
	local global_wrappers;
	-- Per-event wrappers: wrappers[event_name] = wrapper_function
	local wrappers = {};
	-- Event map: event_map[handler_function] = priority_number
	local event_map = {};
	-- Debug hook, if any
	local active_debug_hook = nil;
	-- Called on-demand to build handlers entries
	local function _rebuild_index(self, 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);
		self[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 get_handlers(event)
		return handlers[event];
	end;
	local function add_handlers(self)
		for event, handler in pairs(self) do
			add_handler(event, handler);
		end
	end;
	local function remove_handlers(self)
		for event, handler in pairs(self) do
			remove_handler(event, handler);
		end
	end;
	local function _fire_event(event_name, event_data)
		local h = handlers[event_name];
		if h and not active_debug_hook then
			for i=1,#h do
				local ret = h[i](event_data);
				if ret ~= nil then return ret; end
			end
		elseif h and active_debug_hook then
			for i=1,#h do
				local ret = active_debug_hook(h[i], event_name, event_data);
				if ret ~= nil then return ret; end
			end
		end
	end;
	local function fire_event(event_name, event_data)
		-- luacheck: ignore 432/event_name 432/event_data
		local w = wrappers[event_name] or global_wrappers;
		if w then
			local curr_wrapper = #w;
			local function c(event_name, event_data)
				curr_wrapper = curr_wrapper - 1;
				if curr_wrapper == 0 then
					if global_wrappers == nil or w == global_wrappers then
						return _fire_event(event_name, event_data);
					end
					w, curr_wrapper = global_wrappers, #global_wrappers;
					return w[curr_wrapper](c, event_name, event_data);
				else
					return w[curr_wrapper](c, event_name, event_data);
				end
			end
			return w[curr_wrapper](c, event_name, event_data);
		end
		return _fire_event(event_name, event_data);
	end
	local function add_wrapper(event_name, wrapper)
		local w;
		if event_name == false then
			w = global_wrappers;
			if not w then
				w = {};
				global_wrappers = w;
			end
		else
			w = wrappers[event_name];
			if not w then
				w = {};
				wrappers[event_name] = w;
			end
		end
		w[#w+1] = wrapper;
	end
	local function remove_wrapper(event_name, wrapper)
		local w;
		if event_name == false then
			w = global_wrappers;
		else
			w = wrappers[event_name];
		end
		if not w then return; end
		for i = #w, 1, -1 do
			if w[i] == wrapper then
				t_remove(w, i);
			end
		end
		if #w == 0 then
			if event_name == false then
				global_wrappers = nil;
			else
				wrappers[event_name] = nil;
			end
		end
	end

	local function set_debug_hook(new_hook)
		local old_hook = active_debug_hook;
		active_debug_hook = new_hook;
		return old_hook;
	end

	return {
		add_handler = add_handler;
		remove_handler = remove_handler;
		add_handlers = add_handlers;
		remove_handlers = remove_handlers;
		get_handlers = get_handlers;
		wrappers = {
			add_handler = add_wrapper;
			remove_handler = remove_wrapper;
		};

		add_wrapper = add_wrapper;
		remove_wrapper = remove_wrapper;

		set_debug_hook = set_debug_hook;

		fire_event = fire_event;
		_handlers = handlers;
		_event_map = event_map;
	};
end

return {
	new = new;
};