54 lines
1.8 KiB
JavaScript
54 lines
1.8 KiB
JavaScript
"use strict";
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Object.defineProperty(exports, "__esModule", { value: true });
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exports.mapAsyncIterator = void 0;
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/**
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* Given an AsyncIterable and a callback function, return an AsyncIterator
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* which produces values mapped via calling the callback function.
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*/
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function mapAsyncIterator(iterator, callback, rejectCallback) {
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let $return;
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let abruptClose;
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if (typeof iterator.return === 'function') {
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$return = iterator.return;
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abruptClose = (error) => {
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const rethrow = () => Promise.reject(error);
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return $return.call(iterator).then(rethrow, rethrow);
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};
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}
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function mapResult(result) {
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return result.done ? result : asyncMapValue(result.value, callback).then(iteratorResult, abruptClose);
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}
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let mapReject;
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if (rejectCallback) {
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// Capture rejectCallback to ensure it cannot be null.
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const reject = rejectCallback;
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mapReject = (error) => asyncMapValue(error, reject).then(iteratorResult, abruptClose);
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}
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return {
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next() {
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return iterator.next().then(mapResult, mapReject);
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},
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return() {
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return $return
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? $return.call(iterator).then(mapResult, mapReject)
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: Promise.resolve({ value: undefined, done: true });
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},
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throw(error) {
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if (typeof iterator.throw === 'function') {
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return iterator.throw(error).then(mapResult, mapReject);
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}
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return Promise.reject(error).catch(abruptClose);
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},
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[Symbol.asyncIterator]() {
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return this;
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},
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};
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}
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exports.mapAsyncIterator = mapAsyncIterator;
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function asyncMapValue(value, callback) {
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return new Promise(resolve => resolve(callback(value)));
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}
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function iteratorResult(value) {
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return { value, done: false };
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}
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