ladybird/Userland/Libraries/LibJS/Runtime/IteratorConstructor.cpp

/*
 * Copyright (c) 2023, Tim Flynn <trflynn89@serenityos.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <LibJS/Runtime/AbstractOperations.h>
#include <LibJS/Runtime/Intrinsics.h>
#include <LibJS/Runtime/Iterator.h>
#include <LibJS/Runtime/IteratorConstructor.h>
#include <LibJS/Runtime/IteratorPrototype.h>
#include <LibJS/Runtime/Realm.h>
#include <LibJS/Runtime/VM.h>

namespace JS {

// 3.1.1.1 The Iterator Constructor, https://tc39.es/proposal-iterator-helpers/#sec-iterator-constructor
IteratorConstructor::IteratorConstructor(Realm& realm)
    : Base(realm.vm().names.Iterator.as_string(), realm.intrinsics().function_prototype())
{
}

ThrowCompletionOr<void> IteratorConstructor::initialize(Realm& realm)
{
    MUST_OR_THROW_OOM(Base::initialize(realm));

    auto& vm = this->vm();

    // 3.1.1.2.1 Iterator.prototype, https://tc39.es/proposal-iterator-helpers/#sec-iterator.prototype
    define_direct_property(vm.names.prototype, realm.intrinsics().iterator_prototype(), 0);

    u8 attr = Attribute::Writable | Attribute::Configurable;
    define_native_function(realm, vm.names.from, from, 1, attr);

    define_direct_property(vm.names.length, Value(0), Attribute::Configurable);

    return {};
}

// 3.1.1.1.1 Iterator ( ), https://tc39.es/proposal-iterator-helpers/#sec-iterator
ThrowCompletionOr<Value> IteratorConstructor::call()
{
    auto& vm = this->vm();

    // 1. If NewTarget is undefined or the active function object, throw a TypeError exception.
    return vm.throw_completion<TypeError>(ErrorType::ConstructorWithoutNew, "Iterator");
}

// 3.1.1.1.1 Iterator ( ), https://tc39.es/proposal-iterator-helpers/#sec-iterator
ThrowCompletionOr<NonnullGCPtr<Object>> IteratorConstructor::construct(FunctionObject& new_target)
{
    auto& vm = this->vm();

    // 1. If NewTarget is undefined or the active function object, throw a TypeError exception.
    if (&new_target == this)
        return vm.throw_completion<TypeError>(ErrorType::ClassIsAbstract, "Iterator");

    // 2. Return ? OrdinaryCreateFromConstructor(NewTarget, "%Iterator.prototype%").
    return TRY(ordinary_create_from_constructor<Iterator>(vm, new_target, &Intrinsics::iterator_prototype));
}

// 3.1.1.2.2 Iterator.from ( O ), https://tc39.es/proposal-iterator-helpers/#sec-iterator.from
JS_DEFINE_NATIVE_FUNCTION(IteratorConstructor::from)
{
    auto& realm = *vm.current_realm();

    auto object = vm.argument(0);

    // 1. If O is a String, set O to ! ToObject(O).
    if (object.is_string())
        object = MUST_OR_THROW_OOM(object.to_object(vm));

    // 2. Let iteratorRecord be ? GetIteratorFlattenable(O).
    auto iterator_record = TRY(get_iterator_flattenable(vm, object));

    // 3. Let hasInstance be ? OrdinaryHasInstance(%Iterator%, iteratorRecord.[[Iterator]]).
    auto has_instance = TRY(ordinary_has_instance(vm, iterator_record.iterator, realm.intrinsics().iterator_constructor()));

    // 4. If hasInstance is true, then
    if (has_instance.is_boolean() && has_instance.as_bool()) {
        // a. Return iteratorRecord.[[Iterator]].
        return iterator_record.iterator;
    }

    // 5. Let wrapper be OrdinaryObjectCreate(%WrapForValidIteratorPrototype%, « [[Iterated]] »).
    // 6. Set wrapper.[[Iterated]] to iteratorRecord.
    auto wrapper = MUST_OR_THROW_OOM(Iterator::create(realm, realm.intrinsics().wrap_for_valid_iterator_prototype(), move(iterator_record)));

    // 7. Return wrapper.
    return wrapper;
}

}