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/**
* part of Hachette
* Facilitate listening to events
*
* Copyright (C) 2021 Wojtek Kosior
* Redistribution terms are gathered in the `copyright' file.
*/
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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