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// Copyright 2023 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 iterator {
macro NewJSValidIteratorWrapper(
implicit context: Context)(
underlying: IteratorRecord): JSValidIteratorWrapper {
return new JSValidIteratorWrapper{
map: *NativeContextSlot(ContextSlot::VALID_ITERATOR_WRAPPER_MAP_INDEX),
properties_or_hash: kEmptyFixedArray,
elements: kEmptyFixedArray,
underlying: underlying
};
}
// https://tc39.es/proposal-iterator-helpers/#sec-getiteratorflattenable
transitioning macro GetIteratorFlattenable(
implicit context: Context)(obj: JSReceiver|String): IteratorRecord {
// 1. If obj is not an Object, then
// a. If stringHandling is reject-strings or obj is not a String, throw a
// TypeError exception.
// (Done by caller.)
let iterator: JSAny;
try {
// 2. Let method be ? GetMethod(obj, @@iterator).
const method = GetMethod(obj, IteratorSymbolConstant())
otherwise IfNullOrUndefined;
// 4. Else (method is not undefined),
// a. Let iterator be ? Call(method, obj).
iterator = Call(context, method, obj);
} label IfNullOrUndefined {
// 3. If method is undefined, then
// a. Let iterator be obj.
iterator = obj;
}
// 5. If iterator is not an Object, throw a TypeError exception.
const iteratorObj = Cast<JSReceiver>(iterator)
otherwise ThrowTypeError(MessageTemplate::kNotIterable, obj);
// 6. Return ? GetIteratorDirect(iterator).
return GetIteratorDirect(iteratorObj);
}
// https://tc39.es/proposal-iterator-helpers/#sec-iterator.from
transitioning javascript builtin IteratorFrom(
js-implicit context: NativeContext, receiver: JSAny)(
objArg: JSAny): JSReceiver {
// GetIteratorFlattenable below accepts either Objects or Strings (without
// wrapping) with the iterate-strings parameter. The type checking is done by
// the caller of GetIteratorFlattenable.
let obj: JSReceiver|String;
typeswitch (objArg) {
case (o: String): {
obj = o;
}
case (o: JSReceiver): {
obj = o;
}
case (JSAny): {
ThrowTypeError(MessageTemplate::kCalledOnNonObject, 'Iterator.from');
}
}
// 1. Let iteratorRecord be ? GetIteratorFlattenable(O, iterate-strings).
const iteratorRecord = GetIteratorFlattenable(obj);
// 2. Let hasInstance be ? OrdinaryHasInstance(%Iterator%,
// iteratorRecord.[[Iterator]]).
const hasInstance = function::OrdinaryHasInstance(
context, GetIteratorFunction(), iteratorRecord.object);
// 3. If hasInstance is true, then
if (hasInstance == True) {
// a. Return iteratorRecord.[[Iterator]].
return iteratorRecord.object;
}
// 4. Let wrapper be OrdinaryObjectCreate(%WrapForValidIteratorPrototype%, «
// [[Iterated]] »).
// 5. Set wrapper.[[Iterated]] to iteratorRecord.
// 6. Return wrapper.
return NewJSValidIteratorWrapper(iteratorRecord);
}
// https://tc39.es/proposal-iterator-helpers/#sec-wrapforvaliditeratorprototype.next
transitioning javascript builtin WrapForValidIteratorPrototypeNext(
js-implicit context: NativeContext, receiver: JSAny)(): JSAny {
// 1. Let O be this value.
// 2. Perform ? RequireInternalSlot(O, [[Iterated]]).
const o = Cast<JSValidIteratorWrapper>(receiver) otherwise ThrowTypeError(
MessageTemplate::kIncompatibleMethodReceiver,
'%WrapForValidIteratorPrototype%.next', receiver);
// 3. Let iteratorRecord be O.[[Iterated]].
const iteratorRecord = o.underlying;
// 4. Return ? Call(iteratorRecord.[[NextMethod]],
// iteratorRecord.[[Iterator]]).
return Call(context, iteratorRecord.next, iteratorRecord.object);
}
// https://tc39.es/proposal-iterator-helpers/#sec-wrapforvaliditeratorprototype.return
transitioning javascript builtin WrapForValidIteratorPrototypeReturn(
js-implicit context: NativeContext, receiver: JSAny)(): JSAny {
try {
// 1. Let O be this value.
// 2. Perform ? RequireInternalSlot(O, [[Iterated]]).
const o = Cast<JSValidIteratorWrapper>(receiver) otherwise ThrowTypeError(
MessageTemplate::kIncompatibleMethodReceiver,
'%WrapForValidIteratorPrototype%.return', receiver);
// 3. Let iterator be O.[[Iterated]].[[Iterator]].
const iterator = o.underlying.object;
// 4. Assert: iterator is an Object.
// 5. Let returnMethod be ? GetMethod(iterator, "return").
const returnMethod =
GetMethod(iterator, kReturnString) otherwise ReturnMethodUndefined;
// 7. Return ? Call(returnMethod, iterator).
return Call(context, returnMethod, iterator);
} label ReturnMethodUndefined {
// 6. If returnMethod is undefined, then
// a. Return CreateIterResultObject(undefined, true).
return AllocateJSIteratorResult(Undefined, True);
}
}
} // namespace iterator
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