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LibJS: Move GetObjectPropertyIterator impl to CommonImplementations

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Simon Wanner 2023-10-29 21:15:52 +01:00 • committed by Andreas Kling
parent 25642dfe87
commit ad81bf47bb
3 changed files with 90 additions and 84 deletions
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85
Userland/Libraries/LibJS/Bytecode/Interpreter.cpp
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@ -1143,92 +1143,9 @@ ThrowCompletionOr<void> GetMethod::execute_impl(Bytecode::Interpreter& interpret
return {};
}
// 14.7.5.9 EnumerateObjectProperties ( O ), https://tc39.es/ecma262/#sec-enumerate-object-properties
ThrowCompletionOr<void> GetObjectPropertyIterator::execute_impl(Bytecode::Interpreter& interpreter) const
{
// While the spec does provide an algorithm, it allows us to implement it ourselves so long as we meet the following invariants:
// 1- Returned property keys do not include keys that are Symbols
// 2- Properties of the target object may be deleted during enumeration. A property that is deleted before it is processed by the iterator's next method is ignored
// 3- If new properties are added to the target object during enumeration, the newly added properties are not guaranteed to be processed in the active enumeration
// 4- A property name will be returned by the iterator's next method at most once in any enumeration.
// 5- Enumerating the properties of the target object includes enumerating properties of its prototype, and the prototype of the prototype, and so on, recursively;
// but a property of a prototype is not processed if it has the same name as a property that has already been processed by the iterator's next method.
// 6- The values of [[Enumerable]] attributes are not considered when determining if a property of a prototype object has already been processed.
// 7- The enumerable property names of prototype objects must be obtained by invoking EnumerateObjectProperties passing the prototype object as the argument.
// 8- EnumerateObjectProperties must obtain the own property keys of the target object by calling its [[OwnPropertyKeys]] internal method.
// 9- Property attributes of the target object must be obtained by calling its [[GetOwnProperty]] internal method
// Invariant 3 effectively allows the implementation to ignore newly added keys, and we do so (similar to other implementations).
auto& vm = interpreter.vm();
auto object = TRY(interpreter.accumulator().to_object(vm));
// Note: While the spec doesn't explicitly require these to be ordered, it says that the values should be retrieved via OwnPropertyKeys,
// so we just keep the order consistent anyway.
OrderedHashTable<PropertyKey> properties;
OrderedHashTable<PropertyKey> non_enumerable_properties;
HashTable<NonnullGCPtr<Object>> seen_objects;
// Collect all keys immediately (invariant no. 5)
for (auto object_to_check = GCPtr { object.ptr() }; object_to_check && !seen_objects.contains(*object_to_check); object_to_check = TRY(object_to_check->internal_get_prototype_of())) {
seen_objects.set(*object_to_check);
for (auto& key : TRY(object_to_check->internal_own_property_keys())) {
if (key.is_symbol())
continue;
auto property_key = TRY(PropertyKey::from_value(vm, key));
// If there is a non-enumerable property higher up the prototype chain with the same key,
// we mustn't include this property even if it's enumerable (invariant no. 5 and 6)
if (non_enumerable_properties.contains(property_key))
continue;
if (properties.contains(property_key))
continue;
auto descriptor = TRY(object_to_check->internal_get_own_property(property_key));
if (!*descriptor->enumerable)
non_enumerable_properties.set(move(property_key));
else
properties.set(move(property_key));
}
}
IteratorRecord iterator {
.iterator = object,
.next_method = NativeFunction::create(
interpreter.realm(),
[items = move(properties)](VM& vm) mutable -> ThrowCompletionOr<Value> {
auto& realm = *vm.current_realm();
auto iterated_object_value = vm.this_value();
if (!iterated_object_value.is_object())
return vm.throw_completion<InternalError>("Invalid state for GetObjectPropertyIterator.next"sv);
auto& iterated_object = iterated_object_value.as_object();
auto result_object = Object::create(realm, nullptr);
while (true) {
if (items.is_empty()) {
result_object->define_direct_property(vm.names.done, JS::Value(true), default_attributes);
return result_object;
}
auto key = items.take_first();
// If the property is deleted, don't include it (invariant no. 2)
if (!TRY(iterated_object.has_property(key)))
continue;
result_object->define_direct_property(vm.names.done, JS::Value(false), default_attributes);
if (key.is_number())
result_object->define_direct_property(vm.names.value, PrimitiveString::create(vm, TRY_OR_THROW_OOM(vm, String::number(key.as_number()))), default_attributes);
else if (key.is_string())
result_object->define_direct_property(vm.names.value, PrimitiveString::create(vm, key.as_string()), default_attributes);
else
VERIFY_NOT_REACHED(); // We should not have non-string/number keys.
return result_object;
}
},
1,
vm.names.next),
.done = false,
};
interpreter.accumulator() = iterator_to_object(vm, move(iterator));
interpreter.accumulator() = TRY(get_object_property_iterator(interpreter.vm(), interpreter.accumulator()));
return {};
}