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// |reftest| async
// Copyright (C) 2019 André Bargull. All rights reserved.
// This code is governed by the BSD license found in the LICENSE file.
/*---
esid: sec-generator-function-definitions-runtime-semantics-evaluation
description: >
Return resumption value is awaited upon and hence is treated as a thenable.
info: |
15.5.5 Runtime Semantics: Evaluation
YieldExpression : yield* AssignmentExpression
...
7. Repeat,
a. If received.[[Type]] is normal, then
i. Let innerResult be ? Call(iteratorRecord.[[NextMethod]], iteratorRecord.[[Iterator]],
« received.[[Value]] »).
ii. If generatorKind is async, then set innerResult to ? Await(innerResult).
...
vi. If generatorKind is async, then set received to AsyncGeneratorYield(? IteratorValue(innerResult)).
...
...
c. Else,
i. Assert: received.[[Type]] is return.
ii. Let return be ? GetMethod(iterator, "return").
iii. If return is undefined, then
1. If generatorKind is async, then set received.[[Value]] to ? Await(received.[[Value]]).
2. Return Completion(received).
...
27.6.3.8 AsyncGeneratorYield ( value )
...
12. If queue is not empty, then
...
13. Else,
...
c. Set the code evaluation state of genContext such that when evaluation is resumed with a
Completion resumptionValue the following steps will be performed:
i. Return ? AsyncGeneratorUnwrapYieldResumption(resumptionValue).
27.6.3.7 AsyncGeneratorUnwrapYieldResumption ( resumptionValue )
...
2. Let awaited be Completion(Await(resumptionValue.[[Value]])).
...
6.2.3.1 Await
...
2. Let promise be ? PromiseResolve(%Promise%, « value »).
...
27.2.4.7.1 PromiseResolve ( C, x )
...
2. Let promiseCapability be ? NewPromiseCapability(C).
3. Perform ? Call(promiseCapability.[[Resolve]], undefined, « x »).
...
27.2.1.5 NewPromiseCapability ( C )
...
7. Let promise be ? Construct(C, « executor »).
...
27.2.3.1 Promise ( executor )
...
8. Let resolvingFunctions be CreateResolvingFunctions(promise).
...
27.2.1.3 CreateResolvingFunctions ( promise )
...
2. Let stepsResolve be the algorithm steps defined in Promise Resolve Functions (25.6.1.3.2).
3. Let resolve be CreateBuiltinFunction(stepsResolve, « [[Promise]], [[AlreadyResolved]] »).
...
27.2.1.3.2 Promise Resolve Functions
...
9. Let then be Get(resolution, "then").
...
includes: [compareArray.js]
flags: [async]
features: [async-iteration]
---*/
var expected = [
"start",
// `Await(innerResult)` promise resolved.
"tick 1",
// "then" of `resumptionValue.[[Value]]` accessed.
"get then",
// `Await(resumptionValue.[[Value]])` promise resolved.
"tick 2",
// Get iterator "return" method.
"get return",
// "then" of `received.[[Value]]` accessed.
"get then",
// `Await(received.[[Value]])` promise resolved.
"tick 3",
];
var actual = [];
var asyncIter = {
[Symbol.asyncIterator]() {
return this;
},
next() {
return {
done: false,
};
},
get return() {
actual.push("get return");
}
};
async function* f() {
actual.push("start");
yield* asyncIter;
actual.push("stop - never reached");
}
Promise.resolve(0)
.then(() => actual.push("tick 1"))
.then(() => actual.push("tick 2"))
.then(() => actual.push("tick 3"))
.then(() => {
assert.compareArray(actual, expected, "Ticks for return with thenable getter");
}).then($DONE, $DONE);
var it = f();
// Start generator execution.
it.next();
// Stop generator execution.
it.return({
get then() {
actual.push("get then");
}
});
|
