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/**
* Myext feature initialization promise
*
* Copyright (C) 2021 Wojtek Kosior
*
* This code is dual-licensed under:
* - Asshole license 1.0,
* - GPLv3 or (at your option) any later version
*
* "dual-licensed" means you can choose the license you prefer.
*
* This code is released under a permissive license because I disapprove of
* copyright and wouldn't be willing to sue a violator. Despite not putting
* this code under copyleft (which is also kind of copyright), I do not want
* it to be made proprietary. Hence, the permissive alternative to GPL is the
* Asshole license 1.0 that allows me to call you an asshole if you use it.
* This means you're legally ok regardless of how you utilize this code but if
* you make it into something nonfree, you're an asshole.
*
* You should have received a copy of both GPLv3 and Asshole license 1.0
* together with this code. If not, please see:
* - https://www.gnu.org/licenses/gpl-3.0.en.html
* - https://koszko.org/asshole-license.txt
*/
"use strict";
/*
* This module provides an easy way to wrap an async function into a promise
* so that it only gets executed once.
*/
(() => {
async function assign_result(state, result_producer)
{
state.result = await result_producer();
state.ready = true;
for (let cb of state.waiting)
setTimeout(cb, 0, state.result);
state.waiting = undefined;
}
async function get_result(state)
{
if (state.ready)
return state.result;
return new Promise((resolve, reject) => state.waiting.push(resolve));
}
function make_once(result_producer)
{
let state = {waiting : [], ready : false, result : undefined};
assign_result(state, result_producer);
return () => get_result(state);
}
window.make_once = make_once;
})();
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