87 lines
2.3 KiB
JavaScript
87 lines
2.3 KiB
JavaScript
"use strict";
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Object.defineProperty(exports, "__esModule", {
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value: true
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});
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exports.default = mapAsyncIterator;
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var _symbols = require("../polyfills/symbols.js");
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function _defineProperty(obj, key, value) { if (key in obj) { Object.defineProperty(obj, key, { value: value, enumerable: true, configurable: true, writable: true }); } else { obj[key] = value; } return obj; }
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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(iterable, callback, rejectCallback) {
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// $FlowFixMe[prop-missing]
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var iteratorMethod = iterable[_symbols.SYMBOL_ASYNC_ITERATOR];
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var iterator = iteratorMethod.call(iterable);
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var $return;
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var abruptClose;
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if (typeof iterator.return === 'function') {
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$return = iterator.return;
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abruptClose = function abruptClose(error) {
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var rethrow = function rethrow() {
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return Promise.reject(error);
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};
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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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var mapReject;
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if (rejectCallback) {
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// Capture rejectCallback to ensure it cannot be null.
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var reject = rejectCallback;
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mapReject = function mapReject(error) {
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return asyncMapValue(error, reject).then(iteratorResult, abruptClose);
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};
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}
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/* TODO: Flow doesn't support symbols as keys:
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https://github.com/facebook/flow/issues/3258 */
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return _defineProperty({
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next: function next() {
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return iterator.next().then(mapResult, mapReject);
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},
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return: function _return() {
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return $return ? $return.call(iterator).then(mapResult, mapReject) : Promise.resolve({
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value: undefined,
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done: true
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});
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},
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throw: function _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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}, _symbols.SYMBOL_ASYNC_ITERATOR, function () {
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return this;
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});
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}
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function asyncMapValue(value, callback) {
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return new Promise(function (resolve) {
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return resolve(callback(value));
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});
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}
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function iteratorResult(value) {
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return {
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value: value,
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done: false
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};
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}
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