blob: 23a7efc00ac4785a4a64f27d10499e18ec76898f [file] [log] [blame]
// Copyright 2019 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include 'src/builtins/builtins-promise-gen.h'
namespace promise {
// https://tc39.es/ecma262/#sec-promise.race
transitioning javascript builtin
PromiseRace(
js-implicit context: Context, receiver: JSAny)(iterable: JSAny): JSAny {
const receiver = Cast<JSReceiver>(receiver)
otherwise ThrowTypeError(MessageTemplate::kCalledOnNonObject, 'Promise.race');
const nativeContext = LoadNativeContext(context);
// Let promiseCapability be ? NewPromiseCapability(C).
// Don't fire debugEvent so that forwarding the rejection through all does
// not trigger redundant ExceptionEvents
const capability = NewPromiseCapability(receiver, False);
const resolve = capability.resolve;
const reject = capability.reject;
const promise = capability.promise;
// NewPromiseCapability guarantees that receiver is Constructor.
assert(Is<Constructor>(receiver));
const constructor = UnsafeCast<Constructor>(receiver);
// For catch prediction, don't treat the .then calls as handling it;
// instead, recurse outwards.
if (IsDebugActive()) deferred {
SetPropertyStrict(context, reject, kPromiseForwardingHandlerSymbol, True);
}
try {
let promiseResolveFunction: JSAny;
let i: iterator::IteratorRecord;
try {
// Let promiseResolve be GetPromiseResolve(C).
// IfAbruptRejectPromise(promiseResolve, promiseCapability).
promiseResolveFunction = GetPromiseResolve(nativeContext, constructor);
// Let iterator be GetIterator(iterable).
// IfAbruptRejectPromise(iterator, promiseCapability).
i = iterator::GetIterator(iterable);
} catch (e) deferred {
goto Reject(e);
}
// Let result be PerformPromiseRace(iteratorRecord, C, promiseCapability).
try {
const fastIteratorResultMap = *NativeContextSlot(
nativeContext, ContextSlot::ITERATOR_RESULT_MAP_INDEX);
while (true) {
let nextValue: JSAny;
try {
// Let next be IteratorStep(iteratorRecord.[[Iterator]]).
// If next is an abrupt completion, set iteratorRecord.[[Done]] to
// true. ReturnIfAbrupt(next).
const next: JSReceiver = iterator::IteratorStep(
i, fastIteratorResultMap) otherwise return promise;
// Let nextValue be IteratorValue(next).
// If nextValue is an abrupt completion, set iteratorRecord.[[Done]]
// to true.
// ReturnIfAbrupt(nextValue).
nextValue = iterator::IteratorValue(next, fastIteratorResultMap);
} catch (e) {
goto Reject(e);
}
// Let nextPromise be ? Call(constructor, _promiseResolve_, «
// nextValue »).
const nextPromise =
CallResolve(constructor, promiseResolveFunction, nextValue);
// Perform ? Invoke(nextPromise, "then", « resolveElement,
// resultCapability.[[Reject]] »).
const then = GetProperty(nextPromise, kThenString);
const thenResult = Call(
context, then, nextPromise, UnsafeCast<JSAny>(resolve),
UnsafeCast<JSAny>(reject));
// For catch prediction, mark that rejections here are semantically
// handled by the combined Promise.
if (IsDebugActive() && !Is<JSPromise>(promise)) deferred {
SetPropertyStrict(
context, thenResult, kPromiseHandledBySymbol, promise);
}
}
} catch (e) deferred {
iterator::IteratorCloseOnException(i);
goto Reject(e);
}
} label Reject(exception: Object) deferred {
Call(
context, UnsafeCast<JSAny>(reject), Undefined,
UnsafeCast<JSAny>(exception));
return promise;
}
unreachable;
}
}