yield-star-async-from-sync-iterator-inaccessible.js (1913B)
1 // |reftest| async 2 // Copyright (C) 2019 André Bargull. All rights reserved. 3 // This code is governed by the BSD license found in the LICENSE file. 4 5 /*--- 6 esid: sec-createasyncfromsynciterator 7 description: > 8 Async-from-Sync Iterator instances are not accessible from user code. 9 info: | 10 25.1.4.1 CreateAsyncFromSyncIterator ( syncIteratorRecord ) 11 1. Let asyncIterator be ! ObjectCreate(%AsyncFromSyncIteratorPrototype%, « [[SyncIteratorRecord]] »). 12 2. Set asyncIterator.[[SyncIteratorRecord]] to syncIteratorRecord. 13 3. Let nextMethod be ! Get(asyncIterator, "next"). 14 4. Let iteratorRecord be Record { [[Iterator]]: asyncIterator, [[NextMethod]]: nextMethod, [[Done]]: false }. 15 5. Return iteratorRecord. 16 17 14.4.14 Runtime Semantics: Evaluation 18 YieldExpression : yield * AssignmentExpression 19 1. Let generatorKind be ! GetGeneratorKind(). 20 ... 21 4. Let iteratorRecord be ? GetIterator(value, generatorKind). 22 ... 23 24 7.4.1 GetIterator ( obj [ , hint [ , method ] ] ) 25 ... 26 3. If method is not present, then 27 a. If hint is async, then 28 i. Set method to ? GetMethod(obj, @@asyncIterator). 29 ii. If method is undefined, then 30 1. Let syncMethod be ? GetMethod(obj, @@iterator). 31 2. Let syncIteratorRecord be ? GetIterator(obj, sync, syncMethod). 32 3. Return ? CreateAsyncFromSyncIterator(syncIteratorRecord). 33 ... 34 35 flags: [async] 36 features: [async-iteration] 37 ---*/ 38 39 var AsyncIteratorPrototype = Object.getPrototypeOf(async function*(){}.constructor.prototype.prototype); 40 41 Object.defineProperty(AsyncIteratorPrototype, Symbol.iterator, { 42 get() { 43 throw new Error("@@iterator accessed"); 44 } 45 }); 46 47 Object.defineProperty(AsyncIteratorPrototype, Symbol.asyncIterator, { 48 get() { 49 throw new Error("@@asyncIterator accessed"); 50 } 51 }); 52 53 async function* g() { 54 yield* []; 55 } 56 g().next().then(() => $DONE(), $DONE);