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/**
* This file is part of Haketilo.
*
* Function: Facilitate listening to (internal, self-generated) events.
*
* Copyright (C) 2021 Wojtek Kosior
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* As additional permission under GNU GPL version 3 section 7, you
* may distribute forms of that code without the copy of the GNU
* GPL normally required by section 4, provided you include this
* license notice and, in case of non-source distribution, a URL
* through which recipients can access the Corresponding Source.
* If you modify file(s) with this exception, you may extend this
* exception to your version of the file(s), but you are not
* obligated to do so. If you do not wish to do so, delete this
* exception statement from your version.
*
* As a special exception to the GPL, any HTML file which merely
* makes function calls to this code, and for that purpose
* includes it by reference shall be deemed a separate work for
* copyright law purposes. If you modify this code, you may extend
* this exception to your version of the code, but you are not
* obligated to do so. If you do not wish to do so, delete this
* exception statement from your version.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*
* I, Wojtek Kosior, thereby promise not to sue for violation of this file's
* license. Although I request that you do not make use this code in a
* proprietary program, I am not going to enforce this in court.
*/
const make = (value=undefined) => ({value, listeners: new Set()});
const subscribe = (observable, cb) => observable.listeners.add(cb);
const unsubscribe = (observable, cb) => observable.listeners.delete(cb);
const silent_set = (observable, value) => observable.value = value;
const broadcast = (observable, ...values) =>
observable.listeners.forEach(cb => cb(...values));
function set(observable, value)
{
const old_value = observable.value;
silent_set(observable, value);
broadcast(observable, value, old_value);
}
const observables = {make, subscribe, unsubscribe, broadcast, silent_set, set};
/*
* EXPORTS_START
* EXPORT observables
* EXPORTS_END
*/
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