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nicolo-ribaudolightmare
nicolo-ribaudo
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lightmare
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Await promises from sync iterators with for-await (#13824)
Co-authored-by: Mickey Rose <[email protected]>
1 parent 6029252 commit b9ea196

14 files changed

Lines changed: 186 additions & 41 deletions

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‎packages/babel-helpers/src/helpers-generated.ts‎

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import template from "@babel/template";
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export const asyncIterator = {
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minVersion: "7.15.9",
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ast: () =>
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template.program.ast(
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'\nexport default function _asyncIterator(iterable) {\n var method, async, sync;\n if (typeof Symbol !== "undefined") {\n async = Symbol.asyncIterator;\n sync = Symbol.iterator;\n }\n do {\n if (!sync) {\n async = "@@asyncIterator";\n sync = "@@iterator";\n }\n if (async && (method = iterable[async]) != null) {\n return method.call(iterable);\n }\n if ((method = iterable[sync]) != null) {\n return new AsyncFromSyncIterator(method.call(iterable));\n }\n } while (!(sync === "@@iterator" || (sync = null)));\n throw new TypeError("Object is not async iterable");\n}\nfunction AsyncFromSyncIterator(s) {\n AsyncFromSyncIterator = function (s) {\n this.s = s;\n this.n = s.next;\n };\n AsyncFromSyncIterator.prototype = {\n s: null,\n n: null,\n next: function () {\n return AsyncFromSyncIteratorContinuation(this.n.apply(this.s, arguments));\n },\n return: function (value) {\n var ret = this.s.return;\n if (ret === undefined) {\n return Promise.resolve({ value: value, done: true });\n }\n return AsyncFromSyncIteratorContinuation(ret.apply(this.s, arguments));\n },\n throw: function (value) {\n var thr = this.s.return;\n if (thr === undefined) return Promise.reject(value);\n return AsyncFromSyncIteratorContinuation(thr.apply(this.s, arguments));\n },\n };\n function AsyncFromSyncIteratorContinuation(r) {\n \n if (Object(r) !== r) {\n return Promise.reject(new TypeError(r + " is not an object."));\n }\n var done = r.done;\n return Promise.resolve(r.value).then(function (value) {\n return { value: value, done: done };\n });\n }\n return new AsyncFromSyncIterator(s);\n}\n',
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),
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};
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export const jsx = {
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minVersion: "7.0.0-beta.0",
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ast: () =>

‎packages/babel-helpers/src/helpers.ts‎

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@@ -16,20 +16,6 @@ const helper = (minVersion: string) => (tpl: TemplateStringsArray) => ({
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ast: () => template.program.ast(tpl),
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});
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helpers.asyncIterator = helper("7.0.0-beta.0")`
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export default function _asyncIterator(iterable) {
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var method;
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if (typeof Symbol !== "undefined") {
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if (Symbol.asyncIterator) method = iterable[Symbol.asyncIterator];
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if (method == null && Symbol.iterator) method = iterable[Symbol.iterator];
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}
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if (method == null) method = iterable["@@asyncIterator"];
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if (method == null) method = iterable["@@iterator"]
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if (method == null) throw new TypeError("Object is not async iterable");
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return method.call(iterable);
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}
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`;
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helpers.AwaitValue = helper("7.0.0-beta.0")`
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export default function _AwaitValue(value) {
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this.wrapped = value;

‎packages/babel-helpers/src/helpers/asyncIterator.js‎

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/* @minVersion 7.15.9 */
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export default function _asyncIterator(iterable) {
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var method,
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async,
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sync,
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retry = 2;
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if (typeof Symbol !== "undefined") {
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async = Symbol.asyncIterator;
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sync = Symbol.iterator;
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}
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while (retry--) {
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if (async && (method = iterable[async]) != null) {
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return method.call(iterable);
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}
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if (sync && (method = iterable[sync]) != null) {
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return new AsyncFromSyncIterator(method.call(iterable));
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}
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async = "@@asyncIterator";
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sync = "@@iterator";
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}
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throw new TypeError("Object is not async iterable");
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}
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function AsyncFromSyncIterator(s) {
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AsyncFromSyncIterator = function (s) {
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this.s = s;
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this.n = s.next;
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};
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AsyncFromSyncIterator.prototype = {
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/* SyncIterator */ s: null,
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/* SyncIterator.[[Next]] */ n: null,
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next: function () {
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return AsyncFromSyncIteratorContinuation(this.n.apply(this.s, arguments));
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},
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return: function (value) {
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var ret = this.s.return;
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if (ret === undefined) {
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return Promise.resolve({ value: value, done: true });
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}
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return AsyncFromSyncIteratorContinuation(ret.apply(this.s, arguments));
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},
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throw: function (value) {
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var thr = this.s.return;
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if (thr === undefined) return Promise.reject(value);
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return AsyncFromSyncIteratorContinuation(thr.apply(this.s, arguments));
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},
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};
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function AsyncFromSyncIteratorContinuation(r) {
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// This step is _before_ calling AsyncFromSyncIteratorContinuation in the spec.
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if (Object(r) !== r) {
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return Promise.reject(new TypeError(r + " is not an object."));
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}
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var done = r.done;
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return Promise.resolve(r.value).then(function (value) {
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return { value: value, done: done };
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});
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}
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return new AsyncFromSyncIterator(s);
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}

‎packages/babel-plugin-proposal-async-generator-functions/test/fixtures/for-await/create-async-from-sync-iterator/exec.js‎

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async function* fn() {
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for await (const result of [Promise.resolve("ok")]) {
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return { result };
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}
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}
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return fn().next().then(result => {
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expect(result).toEqual({
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done: true,
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value: { result: "ok" }
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});
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});

‎packages/babel-plugin-proposal-async-generator-functions/test/fixtures/for-await/create-async-from-sync-iterator/input.js‎

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async function* fn() {
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for await (const result of [Promise.resolve("ok")]) {
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return { result };
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}
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}

‎packages/babel-plugin-proposal-async-generator-functions/test/fixtures/for-await/create-async-from-sync-iterator/options.json‎

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{
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"plugins": ["proposal-async-generator-functions"],
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"parserOpts": {
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"allowReturnOutsideFunction": true
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}
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}

‎packages/babel-plugin-proposal-async-generator-functions/test/fixtures/for-await/create-async-from-sync-iterator/output.js‎

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function fn() {
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return _fn.apply(this, arguments);
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}
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function _fn() {
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_fn = babelHelpers.wrapAsyncGenerator(function* () {
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var _iteratorAbruptCompletion = false;
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var _didIteratorError = false;
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var _iteratorError;
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try {
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for (var _iterator = babelHelpers.asyncIterator([Promise.resolve("ok")]), _step; _iteratorAbruptCompletion = !(_step = yield babelHelpers.awaitAsyncGenerator(_iterator.next())).done; _iteratorAbruptCompletion = false) {
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const result = _step.value;
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return {
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result
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};
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}
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} catch (err) {
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_didIteratorError = true;
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_iteratorError = err;
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} finally {
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try {
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if (_iteratorAbruptCompletion && _iterator.return != null) {
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yield babelHelpers.awaitAsyncGenerator(_iterator.return());
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}
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} finally {
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if (_didIteratorError) {
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throw _iteratorError;
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}
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}
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}
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});
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return _fn.apply(this, arguments);
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}

‎packages/babel-plugin-proposal-async-generator-functions/test/fixtures/yield-star/create-async-from-sync-iterator/exec.js‎

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async function* fn() {
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yield* [Promise.resolve("ok")] // CreateAsyncFromSyncIterator
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}
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return fn().next().then(result => {
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expect(result).toEqual({ value: "ok", done: false });
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});

‎packages/babel-plugin-proposal-async-generator-functions/test/fixtures/yield-star/create-async-from-sync-iterator/input.js‎

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async function* fn() {
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yield* [Promise.resolve("ok")] // CreateAsyncFromSyncIterator
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}

‎packages/babel-plugin-proposal-async-generator-functions/test/fixtures/yield-star/create-async-from-sync-iterator/options.json‎

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{
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"plugins": ["proposal-async-generator-functions"],
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"parserOpts": {
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"allowReturnOutsideFunction": true
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}
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}

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