LibJS: Add spec comments to SetConstructor

Userland/Libraries/LibJS/Runtime/SetConstructor.cpp

@@ -37,34 +37,52 @@ ThrowCompletionOr<void> SetConstructor::initialize(Realm& realm)
 ThrowCompletionOr<Value> SetConstructor::call()
 {
  auto& vm = this->vm();
+
+ // 1. If NewTarget is undefined, throw a TypeError exception.
  return vm.throw_completion<TypeError>(ErrorType::ConstructorWithoutNew, vm.names.Set);
 }
 
 // 24.2.1.1 Set ( [ iterable ] ), https://tc39.es/ecma262/#sec-set-iterable
 ThrowCompletionOr<NonnullGCPtr<Object>> SetConstructor::construct(FunctionObject& new_target)
 {
  auto& vm = this->vm();
+ auto iterable = vm.argument(0);
 
+ // 2. Let set be ? OrdinaryCreateFromConstructor(NewTarget, "%Set.prototype%", « [[SetData]] »).
  auto set = TRY(ordinary_create_from_constructor<Set>(vm, new_target, &Intrinsics::set_prototype));
 
- if (vm.argument(0).is_nullish())
+ // 3. Set set.[[SetData]] to a new empty List.
+
+ // 4. If iterable is either undefined or null, return set.
+ if (iterable.is_nullish())
  return set;
 
+ // 5. Let adder be ? Get(set, "add").
  auto adder = TRY(set->get(vm.names.add));
+
+ // 6. If IsCallable(adder) is false, throw a TypeError exception.
  if (!adder.is_function())
  return vm.throw_completion<TypeError>(ErrorType::NotAFunction, "'add' property of Set");
 
- (void)TRY(get_iterator_values(vm, vm.argument(0), [&](Value iterator_value) -> Optional<Completion> {
- TRY(JS::call(vm, adder.as_function(), set, iterator_value));
+ // 7. Let iteratorRecord be ? GetIterator(iterable, sync).
+ // 8. Repeat,
+ // a. Let next be ? IteratorStep(iteratorRecord).
+ // c. Let nextValue be ? IteratorValue(next).
+ (void)TRY(get_iterator_values(vm, iterable, [&](Value next_value) -> Optional<Completion> {
+ // d. Let status be Completion(Call(adder, set, « nextValue »)).
+ // e. IfAbruptCloseIterator(status, iteratorRecord).
+ TRY(JS::call(vm, adder.as_function(), set, next_value));
  return {};
  }));
 
+ // b. If next is false, return set.
  return set;
 }
 
 // 24.2.2.2 get Set [ @@species ], https://tc39.es/ecma262/#sec-get-set-@@species
 JS_DEFINE_NATIVE_FUNCTION(SetConstructor::symbol_species_getter)
 {
+ // 1. Return the this value.
  return vm.this_value();
 }