LibJS: Implement the Temporal.PlainDate constructor

And the simple Temporal.PlainDate.prototype getters, so that the
constructed Temporal.PlainDate may actually be validated.

Libraries/LibJS/Runtime/Temporal/PlainDateConstructor.cpp

@@ -0,0 +1,108 @@
+/*
+ * Copyright (c) 2021, Idan Horowitz <idan.horowitz@serenityos.org>
+ * Copyright (c) 2024, Tim Flynn <trflynn89@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibJS/Runtime/Temporal/Calendar.h>
+#include <LibJS/Runtime/Temporal/PlainDate.h>
+#include <LibJS/Runtime/Temporal/PlainDateConstructor.h>
+
+namespace JS::Temporal {
+
+GC_DEFINE_ALLOCATOR(PlainDateConstructor);
+
+// 3.1 The Temporal.PlainDate Constructor, https://tc39.es/proposal-temporal/#sec-temporal-plaindate-constructor
+PlainDateConstructor::PlainDateConstructor(Realm& realm)
+    : NativeFunction(realm.vm().names.PlainDate.as_string(), realm.intrinsics().function_prototype())
+{
+}
+
+void PlainDateConstructor::initialize(Realm& realm)
+{
+    Base::initialize(realm);
+
+    auto& vm = this->vm();
+
+    // 3.2.1 Temporal.PlainDate.prototype, https://tc39.es/proposal-temporal/#sec-temporal.plaindate.prototype
+    define_direct_property(vm.names.prototype, realm.intrinsics().temporal_plain_date_prototype(), 0);
+
+    u8 attr = Attribute::Writable | Attribute::Configurable;
+    define_native_function(realm, vm.names.from, from, 1, attr);
+    define_native_function(realm, vm.names.compare, compare, 2, attr);
+
+    define_direct_property(vm.names.length, Value(3), Attribute::Configurable);
+}
+
+// 3.1.1 Temporal.PlainDate ( isoYear, isoMonth, isoDay [ , calendar ] ), https://tc39.es/proposal-temporal/#sec-temporal.plaindate
+ThrowCompletionOr<Value> PlainDateConstructor::call()
+{
+    auto& vm = this->vm();
+
+    // 1. If NewTarget is undefined, throw a TypeError exception.
+    return vm.throw_completion<TypeError>(ErrorType::ConstructorWithoutNew, "Temporal.PlainDate");
+}
+
+// 3.1.1 Temporal.PlainDate ( isoYear, isoMonth, isoDay [ , calendar ] ), https://tc39.es/proposal-temporal/#sec-temporal.plaindate
+ThrowCompletionOr<GC::Ref<Object>> PlainDateConstructor::construct(FunctionObject& new_target)
+{
+    auto& vm = this->vm();
+
+    auto iso_year = vm.argument(0);
+    auto iso_month = vm.argument(1);
+    auto iso_day = vm.argument(2);
+    auto calendar_value = vm.argument(3);
+
+    // 2. Let y be ? ToIntegerWithTruncation(isoYear).
+    auto year = TRY(to_integer_with_truncation(vm, iso_year, ErrorType::TemporalInvalidPlainDate));
+
+    // 3. Let m be ? ToIntegerWithTruncation(isoMonth).
+    auto month = TRY(to_integer_with_truncation(vm, iso_month, ErrorType::TemporalInvalidPlainDate));
+
+    // 4. Let d be ? ToIntegerWithTruncation(isoDay).
+    auto day = TRY(to_integer_with_truncation(vm, iso_day, ErrorType::TemporalInvalidPlainDate));
+
+    // 5. If calendar is undefined, set calendar to "iso8601".
+    if (calendar_value.is_undefined())
+        calendar_value = PrimitiveString::create(vm, "iso8601"_string);
+
+    // 6. If calendar is not a String, throw a TypeError exception.
+    if (!calendar_value.is_string())
+        return vm.throw_completion<TypeError>(ErrorType::NotAString, "calendar"sv);
+
+    // 7. Set calendar to ? CanonicalizeCalendar(calendar).
+    auto calendar = TRY(canonicalize_calendar(vm, calendar_value.as_string().utf8_string_view()));
+
+    // 8. If IsValidISODate(y, m, d) is false, throw a RangeError exception.
+    if (!is_valid_iso_date(year, month, day))
+        return vm.throw_completion<RangeError>(ErrorType::TemporalInvalidPlainDate);
+
+    // 9. Let isoDate be CreateISODateRecord(y, m, d).
+    auto iso_date = create_iso_date_record(year, month, day);
+
+    // 10. Return ? CreateTemporalDate(isoDate, calendar, NewTarget).
+    return TRY(create_temporal_date(vm, iso_date, move(calendar), &new_target));
+}
+
+// 3.2.2 3.2.2 Temporal.PlainDate.from ( item [ , options ] ), https://tc39.es/proposal-temporal/#sec-temporal.plaindate.from
+JS_DEFINE_NATIVE_FUNCTION(PlainDateConstructor::from)
+{
+    // 1. Return ? ToTemporalDate(item, options).
+    return TRY(to_temporal_date(vm, vm.argument(0), vm.argument(1)));
+}
+
+// 3.2.3 Temporal.PlainDate.compare ( one, two ), https://tc39.es/proposal-temporal/#sec-temporal.plaindate.compare
+JS_DEFINE_NATIVE_FUNCTION(PlainDateConstructor::compare)
+{
+    // 1. Set one to ? ToTemporalDate(one).
+    auto one = TRY(to_temporal_date(vm, vm.argument(0)));
+
+    // 2. Set two to ? ToTemporalDate(two).
+    auto two = TRY(to_temporal_date(vm, vm.argument(1)));
+
+    // 3. Return 𝔽(CompareISODate(one.[[ISODate]], two.[[ISODate]])).
+    return compare_iso_date(one->iso_date(), two->iso_date());
+}
+
+}