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LibJS: Annotate Promise implementation with spec comments

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I wanted to do this for a long time. The guts of Promise are pretty
complex, and it's easier to understand with the spec right next to it.
Also found a couple of issues along the way :^)
This commit is contained in:
Linus Groh 2021-11-14 00:33:16 +00:00
parent df06552b48
commit 01c2570678
Notes: sideshowbarker 2024-07-18 01:10:03 +09:00
7 changed files with 523 additions and 41 deletions
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45
Userland/Libraries/LibJS/Runtime/PromiseResolvingElementFunctions.cpp
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@ -63,13 +63,20 @@ Value PromiseAllResolveElementFunction::resolve_element()
auto& vm = this->vm();
auto& global_object = this->global_object();
// 8. Set values[index] to x.
m_values.values()[m_index] = vm.argument(0);
// 9. Set remainingElementsCount.[[Value]] to remainingElementsCount.[[Value]] - 1.
// 10. If remainingElementsCount.[[Value]] is 0, then
if (--m_remaining_elements.value == 0) {
auto values_array = Array::create_from(global_object, m_values.values());
// a. Let valuesArray be ! CreateArrayFromList(values).
auto* values_array = Array::create_from(global_object, m_values.values());
// b. Return ? Call(promiseCapability.[[Resolve]], undefined, « valuesArray »).
return TRY_OR_DISCARD(vm.call(*m_capability.resolve, js_undefined(), values_array));
}
// 11. Return undefined.
return js_undefined();
}
@ -88,17 +95,29 @@ Value PromiseAllSettledResolveElementFunction::resolve_element()
auto& vm = this->vm();
auto& global_object = this->global_object();
// 9. Let obj be ! OrdinaryObjectCreate(%Object.prototype%).
auto* object = Object::create(global_object, global_object.object_prototype());
// 10. Perform ! CreateDataPropertyOrThrow(obj, "status", "fulfilled").
MUST(object->create_data_property_or_throw(vm.names.status, js_string(vm, "fulfilled"sv)));
// 11. Perform ! CreateDataPropertyOrThrow(obj, "value", x).
MUST(object->create_data_property_or_throw(vm.names.value, vm.argument(0)));
// 12. Set values[index] to obj.
m_values.values()[m_index] = object;
// 13. Set remainingElementsCount.[[Value]] to remainingElementsCount.[[Value]] - 1.
// 14. If remainingElementsCount.[[Value]] is 0, then
if (--m_remaining_elements.value == 0) {
auto values_array = Array::create_from(global_object, m_values.values());
// a. Let valuesArray be ! CreateArrayFromList(values).
auto* values_array = Array::create_from(global_object, m_values.values());
// b. Return ? Call(promiseCapability.[[Resolve]], undefined, « valuesArray »).
return TRY_OR_DISCARD(vm.call(*m_capability.resolve, js_undefined(), values_array));
}
// 15. Return undefined.
return js_undefined();
}
@ -117,17 +136,29 @@ Value PromiseAllSettledRejectElementFunction::resolve_element()
auto& vm = this->vm();
auto& global_object = this->global_object();
// 9. Let obj be ! OrdinaryObjectCreate(%Object.prototype%).
auto* object = Object::create(global_object, global_object.object_prototype());
// 10. Perform ! CreateDataPropertyOrThrow(obj, "status", "rejected").
MUST(object->create_data_property_or_throw(vm.names.status, js_string(vm, "rejected"sv)));
// 11. Perform ! CreateDataPropertyOrThrow(obj, "reason", x).
MUST(object->create_data_property_or_throw(vm.names.reason, vm.argument(0)));
// 12. Set values[index] to obj.
m_values.values()[m_index] = object;
// 13. Set remainingElementsCount.[[Value]] to remainingElementsCount.[[Value]] - 1.
// 14. If remainingElementsCount.[[Value]] is 0, then
if (--m_remaining_elements.value == 0) {
// a. Let valuesArray be ! CreateArrayFromList(values).
auto values_array = Array::create_from(global_object, m_values.values());
// b. Return ? Call(promiseCapability.[[Resolve]], undefined, « valuesArray »).
return TRY_OR_DISCARD(vm.call(*m_capability.resolve, js_undefined(), values_array));
}
// 15. Return undefined.
return js_undefined();
}
@ -146,14 +177,20 @@ Value PromiseAnyRejectElementFunction::resolve_element()
auto& vm = this->vm();
auto& global_object = this->global_object();
// 8. Set errors[index] to x.
m_values.values()[m_index] = vm.argument(0);
// 9. Set remainingElementsCount.[[Value]] to remainingElementsCount.[[Value]] - 1.
// 10. If remainingElementsCount.[[Value]] is 0, then
if (--m_remaining_elements.value == 0) {
auto errors_array = Array::create_from(global_object, m_values.values());
// a. Let error be a newly created AggregateError object.
auto* error = AggregateError::create(global_object);
// b. Perform ! DefinePropertyOrThrow(error, "errors", PropertyDescriptor { [[Configurable]]: true, [[Enumerable]]: false, [[Writable]]: true, [[Value]]: ! CreateArrayFromList(errors) }).
auto errors_array = Array::create_from(global_object, m_values.values());
MUST(error->define_property_or_throw(vm.names.errors, { .value = errors_array, .writable = true, .enumerable = false, .configurable = true }));
// c. Return ? Call(promiseCapability.[[Reject]], undefined, « error »).
return TRY_OR_DISCARD(vm.call(*m_capability.reject, js_undefined(), error));
}