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// Copyright 2020 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.
namespace runtime {
extern runtime JSWeakRefAddToKeptObjects(implicit context: Context)(JSReceiver):
void;
} // namespace runtime
namespace weakref {
transitioning javascript builtin
WeakRefConstructor(
js-implicit context: NativeContext, receiver: JSAny, newTarget: JSAny,
target: JSFunction)(weakTarget: JSAny): JSWeakRef {
// 1. If NewTarget is undefined, throw a TypeError exception.
if (newTarget == Undefined) {
ThrowTypeError(MessageTemplate::kConstructorNotFunction, 'WeakRef');
}
// 2. If Type(target) is not Object, throw a TypeError exception.
const weakTarget = Cast<JSReceiver>(weakTarget) otherwise
ThrowTypeError(
MessageTemplate::kWeakRefsWeakRefConstructorTargetMustBeObject);
// 3. Let weakRef be ? OrdinaryCreateFromConstructor(NewTarget,
// "%WeakRefPrototype%", « [[WeakRefTarget]] »).
const map = GetDerivedMap(target, UnsafeCast<JSReceiver>(newTarget));
const weakRef = UnsafeCast<JSWeakRef>(AllocateFastOrSlowJSObjectFromMap(map));
// 4. Perfom ! AddToKeptObjects(target).
runtime::JSWeakRefAddToKeptObjects(weakTarget);
// 5. Set weakRef.[[WeakRefTarget]] to target.
weakRef.target = weakTarget;
// 6. Return weakRef.
return weakRef;
}
transitioning javascript builtin
WeakRefDeref(js-implicit context: NativeContext, receiver: JSAny)(): JSAny {
// 1. Let weakRef be the this value.
// 2. Perform ? RequireInternalSlot(weakRef, [[WeakRefTarget]]).
const weakRef = Cast<JSWeakRef>(receiver) otherwise
ThrowTypeError(
MessageTemplate::kIncompatibleMethodReceiver, 'WeakRef.prototype.deref',
receiver);
// 3. Let target be the value of weakRef.[[WeakRefTarget]].
const target = weakRef.target;
// 4. If target is not empty,
// a. Perform ! AddToKeptObjects(target).
// b. Return target.
// 5. Return undefined.
if (target != Undefined) {
// JSWeakRefAddToKeptObjects might allocate and cause a GC, but it
// won't clear `target` since we hold it here on the stack.
runtime::JSWeakRefAddToKeptObjects(UnsafeCast<JSReceiver>(target));
}
return target;
}
} // namespace weakrefs
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