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'use strict';
const pLimit = require('p-limit');
class EndError extends Error {
constructor(value) {
super();
this.value = value;
}
}
// the input can also be a promise, so we `Promise.all()` them both
const finder = el => Promise.all(el).then(val => val[1] === true && Promise.reject(new EndError(val[0])));
module.exports = (iterable, tester, opts) => {
opts = Object.assign({
concurrency: Infinity,
preserveOrder: true
}, opts);
const limit = pLimit(opts.concurrency);
// start all the promises concurrently with optional limit
const items = Array.from(iterable).map(el => [el, limit(() => Promise.resolve(el).then(tester))]);
// check the promises either serially or concurrently
const checkLimit = pLimit(opts.preserveOrder ? 1 : Infinity);
return Promise.all(items.map(el => checkLimit(() => finder(el))))
.then(() => {})
.catch(err => err instanceof EndError ? err.value : Promise.reject(err));
};
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