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event.opa
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event.opa
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/*
Copyright © 2011 MLstate
This file is part of OPA.
OPA is free software: you can redistribute it and/or modify it under the
terms of the GNU Affero General Public License, version 3, as published by
the Free Software Foundation.
OPA is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for
more details.
You should have received a copy of the GNU Affero General Public License
along with OPA. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* Elvis Events
*
* @category UI
* @author David Rajchenbach-Teller, 2011
* @destination PUBLIC
* @stability EXPERIMENTAL
*/
/**
* {1 General definitions}
*/
@abstract type Event.source('a) = Network.network('a)
@abstract type Event.observer = (-> void)
Event =
{{
Source =
{{
/**
* Create a source that won't ever send anything.
*/
empty(): Event.source('a) = (Network.empty())
}}
/**
* Register to be informed whenever a source produces a new event
*/
observe(source: Event.source('a), sink: channel('a)): Event.observer =
(
do Network.add(sink, (source))
(-> Network.remove(sink, (source)))
)
/**
* As [observe], but with a function
*/
callback(source: Event.source('a), sink: 'a -> void): Event.observer =
(
observe(source, Session.make({}, (_, msg -> do sink(msg) {unchanged})))
)
/**
* As [callback], but with the function is automatically unregistered once it has been called
*/
callback_once(source: Event.source('a), sink: 'a -> void): Event.observer =
(
c = Session.make({}, (_, msg -> do sink(msg) {stop}))
observe(source, c)
)
/**
* Broadcast an event to all observers
*/
trigger(source: Event.source('a), event:'a): void =
(
Network.broadcast(event, (source))
)
unobserve(observer: Event.observer): void =
(
(observer)()
)
}}