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EventDispatcher.lua
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EventDispatcher.lua
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--[[
Title: EventDispatcher(Single Listener) and EventSystem(Multiple Listener)
Author(s): Leio, refactored by LiXizhi 2009.11.6, EventSystem added by LiXizhi 2010.9.3
Date: 2008/12/24
Desc: We can use it as a base class or as a member in a class.
EventDispatcher and EventSystem have identical interfaces.
* EventDispatcher only support one listener per event type, and is slightly faster than EventSystem
* EventSystem support multiple listeners per event type, but one needs to be aware of duplicated calls to AddEventListener
use the lib:
------------------------------------------------------------
NPL.load("(gl)script/ide/EventDispatcher.lua");
-- Usage 1: as a member in a class
local events = commonlib.EventDispatcher:new();
local events = commonlib.EventSystem:new();
events:AddEventListener("eventType",function(self, event) commonlib.echo(event) end, events, "global_unique_name_can_be_nil");
events:DispatchEvent({type = "eventType" , data = "as member"});
-- Usage 2: as a base class
local MyClass = commonlib.inherit(commonlib.EventSystem, commonlib.gettable("commonlib.test.event_system_test"));
MyClass:ctor(); -- call this if singleton.
function MyClass:MyCallBack(event)
commonlib.echo(event)
end
local myclassInst = MyClass:new();
myclassInst:AddEventListener("eventType", MyClass.MyCallBack, myclassInst, "global_unique_name_can_be_nil");
myclassInst:DispatchEvent({type = "eventType" , data = "as base class"});
------------------------------------------------------------
]]
local EventDispatcher = commonlib.inherit(nil, commonlib.gettable("commonlib.EventDispatcher"))
--constructor
function EventDispatcher:ctor()
self.event_pools = {}
end
-- add a new listener. Note there can only be one listener per event type
-- @param type: this is the key to event. It can be anything. It is usually string or integer.
-- @param func: the callback function(funcHolder, event) end.
-- @param funcHolder: this is an object that is passed as the first parameter to the callback function.
function EventDispatcher:AddEventListener(type,func,funcHolder)
if(not type or not func)then return end
self.event_pools[type] = {func = func,funcHolder = funcHolder};
end
-- remove listener
function EventDispatcher:RemoveEventListener(type)
if(not type)then return end
self.event_pools[type] = nil;
end
-- has event listener
function EventDispatcher:HasEventListener(type)
if(not type)then return end
if(self.event_pools[type])then
return true;
end
end
-- dispatch the event.
-- @return: the callback return value is also returned.
function EventDispatcher:DispatchEvent(event, ...)
if(not event)then return end
local listener = self.event_pools[event.type]
if(listener)then
local func = listener.func;
local funcHolder = listener.funcHolder;
return func(funcHolder,event, ...)
end
end
-- dispatch the event.
-- @return: the callback return value is also returned.
function EventDispatcher:DispatchEventByType(event_type, event, ...)
if(not event)then return end
local listener = self.event_pools[event_type]
if(listener)then
local func = listener.func;
local funcHolder = listener.funcHolder;
return func(funcHolder,event, ...)
end
end
function EventDispatcher:ClearAllEvents()
self.event_pools = {};
end
-----------------------------------
-- Event system is similar to Event Dispatcher except that it support multiple listeners of the same type.
-----------------------------------
local EventSystem = commonlib.inherit(nil, commonlib.gettable("commonlib.EventSystem"))
function EventSystem.getInstance()
if not EventSystem.sInstance then
EventSystem.sInstance = EventSystem:new();
end
return EventSystem.sInstance;
end
--constructor
function EventSystem:ctor()
self.event_pools = {}
end
-- add a new listener. Note there can only be one listener per event type
-- @param type: this is the key to event. It can be anything. It is usually string or integer.
-- @param func: the callback function(funcHolder, event) end.
-- @param funcHolder: this is an object that is passed as the first parameter to the callback function.
-- @param listener_name: this is an optional paramter. If there is already a listener of the same name, it will be overriden.
function EventSystem:AddEventListener(type,func,funcHolder, listener_name)
if(not type or not func)then return end
local sinks = self.event_pools[type];
if(not sinks) then
sinks = {};
self.event_pools[type] = sinks;
end
local index, handler;
for index, handler in ipairs(sinks) do
if(listener_name and handler.name == listener_name) then
handler.func = func;
handler.funcHolder = funcHolder;
LOG.std("", "debug", "EventSystem", "override listener type %s, name %s", tostring(type), listener_name);
return;
else
if(handler.func == func and handler.funcHolder == funcHolder and handler.name == listener_name) then
LOG.std("", "debug", "EventSystem", "duplicated listener called for %s", tostring(type))
return;
end
end
end
sinks[#sinks + 1] = {func = func, funcHolder = funcHolder, name=listener_name};
end
-- remove listener
function EventSystem:RemoveEventListener(type, func, funcHolder)
if(not type)then return end
if(not func) then
self.event_pools[type] = nil;
else
local sinks = self.event_pools[type];
if(sinks) then
local index, handler;
for index, handler in ipairs(sinks) do
if(handler.func == func and handler.funcHolder == funcHolder ) then
commonlib.removeArrayItem(sinks, index);
return
end
end
end
LOG.std("", "debug", "EventSystem", "there is no matching event listener to remove for %s", tostring(type))
end
end
-- has event listener
function EventSystem:HasEventListener(type, func, funcHolder)
if(not type)then return end
if(self.event_pools[type])then
if(not func) then
return true;
else
local sinks = self.event_pools[type];
if(sinks) then
local index, handler;
for index, handler in ipairs(sinks) do
if(handler.func == func and handler.funcHolder == funcHolder ) then
return true
end
end
end
end
end
end
-- dispatch the event.
-- @return: the callback return value is also returned. if there are multiple listeners, the returned value is the last non-nil return value of the callback function.
function EventSystem:DispatchEvent(event, ...)
if(not event)then return end
local sinks = self.event_pools[event.type];
if(sinks) then
local return_value;
local index, handler;
for index, handler in ipairs(sinks) do
return_value = handler.func(handler.funcHolder, event, ...) or return_value;
end
return return_value;
end
end
function EventSystem:GetEventHandlerCount(event_type)
local sinks = self.event_pools[event_type];
if(sinks) then
return #sinks;
else
return 0;
end
end
-- dispatch the event.
-- @return: the callback return value is also returned.
function EventSystem:DispatchEventByType(event_type, event, ...)
if(not event)then return end
local sinks = self.event_pools[event_type];
if(sinks) then
local index, handler;
for index, handler in ipairs(sinks) do
handler.func(handler.funcHolder, event, ...)
end
end
end
-- clear all. reseting to empty.
function EventSystem:ClearAllEvents()
self.event_pools = {};
end