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#
#
# Nimrod's Runtime Library
# (c) Copyright 2011 Alex Mitchell
#
# See the file "copying.txt", included in this
# distribution, for details about the copyright.
#
## :Author: Alex Mitchell
##
## This module implements an event system that is not dependant on external
## graphical toolkits. It was originally called ``NimEE`` because
## it was inspired by Ptyhon's PyEE module.
type
TEventArgs* = object of TObject ## Base object for event arguments
## that are passed to callback functions.
TEventHandler = tuple[name: string, handlers: seq[proc(e:TEventArgs)]]
PEventHandler* = ref TEventHandler ## An eventhandler for an event.
type
TEventEmitter = object {.pure, final.}
s: seq[PEventHandler]
PEventEmitter* = ref TEventEmitter ## An object that fires events and
## holds event handlers for an object.
EInvalidEvent* = object of EInvalidValue
proc newEventHandler*(name: string): PEventHandler =
## Initializes an EventHandler with the specified name and returns it.
new(result)
result.handlers = @[]
result.name = name
proc addHandler*(handler: PEventHandler, func: proc(e: TEventArgs)) =
## Adds the callback to the specified event handler.
handler.handlers.add(func)
proc removeHandler*(handler: PEventHandler, func: proc(e: TEventArgs)) =
## Removes the callback from the specified event handler.
for i in countup(0, len(handler.handlers) -1):
if func == handler.handlers[i]:
handler.handlers.del(i)
break
proc clearHandlers*(handler: PEventHandler) =
## Clears all of the callbacks from the event handler.
setLen(handler.handlers, 0)
proc getEventhandler(emitter: PEventEmitter, event: string): int =
for k in 0..high(emitter.s):
if emitter.s[k].name == event: return k
return -1
proc on*(emitter: PEventEmitter, event: string, func: proc(e: TEventArgs)) =
## Assigns a event handler with the specified callback. If the event
## doesn't exist, it will be created.
var i = getEventHandler(emitter, event)
if i < 0:
var eh = newEventHandler(event)
addHandler(eh, func)
emitter.s.add(eh)
else:
addHandler(emitter.s[i], func)
proc emit*(emitter: PEventEmitter, eventhandler: PEventHandler,
args: TEventArgs) =
## Fires an event handler with specified event arguments.
for func in items(eventhandler.handlers): func(args)
proc emit*(emitter: PEventEmitter, event: string, args: TEventArgs) =
## Fires an event handler with specified event arguments.
var i = getEventHandler(emitter, event)
if i >= 0:
emit(emitter, emitter.s[i], args)
else:
raise newException(EInvalidEvent, "invalid event: " & event)
proc newEventEmitter*(): PEventEmitter =
## Creates and returns a new EventEmitter.
new(result)
result.s = @[]
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