44 lines
1.2 KiB
JavaScript
44 lines
1.2 KiB
JavaScript
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// Copyright 2021 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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// Async generator builtins that suspend the generator set the is_awaiting bit
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// to 1 before awaiting. This is cleared when resumed. This tests that the bit
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// is set after the await operation successfully completes (i.e. returns the
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// Promise), since it can throw, and that thrown exception can be caught by
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// script. Otherwise the is_awaiting bit won't be cleared.
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// This makes `await new Promise(() => {})` throw.
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Object.defineProperty(Promise.prototype, 'constructor', {
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get() { throw 42; }
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});
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// AsyncGeneratorAwait
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{
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async function *f() {
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try {
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await new Promise(() => {});
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} catch (e) {
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}
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}
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f().next();
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}
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// AsyncGeneratorYield
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{
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async function *f() {
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try {
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yield new Promise(() => {});
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} catch (e) {
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}
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}
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f().next();
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}
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// AsyncGeneratorReturn isn't affected because it's not possible, in script, to
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// catch an error thrown by a return resumption. It'll be caught by the
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// synthetic try-catch around the whole body of the async generator, which will
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// correctly reset the is_awaiting bit.
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