LibJS: Implement Temporal.PlainDateTime.prototype.withCalendar

Userland/Libraries/LibJS/Runtime/Temporal/PlainDateTimePrototype.cpp

@@ -48,6 +48,7 @@ void PlainDateTimePrototype::initialize(GlobalObject& global_object)
     define_native_accessor(vm.names.inLeapYear, in_leap_year_getter, {}, Attribute::Configurable);
 
     u8 attr = Attribute::Writable | Attribute::Configurable;
+    define_native_function(vm.names.withCalendar, with_calendar, 1, attr);
     define_native_function(vm.names.valueOf, value_of, 0, attr);
     define_native_function(vm.names.toPlainDate, to_plain_date, 0, attr);
     define_native_function(vm.names.getISOFields, get_iso_fields, 0, attr);
@@ -349,6 +350,24 @@ JS_DEFINE_NATIVE_FUNCTION(PlainDateTimePrototype::in_leap_year_getter)
     return calendar_in_leap_year(global_object, calendar, *date_time);
 }
 
+// 5.3.25 Temporal.PlainDateTime.prototype.withCalendar ( calendar ), https://tc39.es/proposal-temporal/#sec-temporal.plaindatetime.prototype.withcalendar
+JS_DEFINE_NATIVE_FUNCTION(PlainDateTimePrototype::with_calendar)
+{
+    // 1. Let temporalDateTime be the this value.
+    // 2. Perform ? RequireInternalSlot(temporalDateTime, [[InitializedTemporalDateTime]]).
+    auto* date_time = typed_this(global_object);
+    if (vm.exception())
+        return {};
+
+    // 3. Let calendar be ? ToTemporalCalendar(calendar).
+    auto* calendar = to_temporal_calendar(global_object, vm.argument(0));
+    if (vm.exception())
+        return {};
+
+    // 4. Return ? CreateTemporalDateTime(temporalDateTime.[[ISOYear]], temporalDateTime.[[ISOMonth]], temporalDateTime.[[ISODay]], temporalDateTime.[[ISOHour]], temporalDateTime.[[ISOMinute]], temporalDateTime.[[ISOSecond]], temporalDateTime.[[ISOMillisecond]], temporalDateTime.[[ISOMicrosecond]], temporalDateTime.[[ISONanosecond]], calendar).
+    return create_temporal_date_time(global_object, date_time->iso_year(), date_time->iso_month(), date_time->iso_day(), date_time->iso_hour(), date_time->iso_minute(), date_time->iso_second(), date_time->iso_millisecond(), date_time->iso_microsecond(), date_time->iso_nanosecond(), *calendar);
+}
+
 // 5.3.35 Temporal.PlainDateTime.prototype.valueOf ( ), https://tc39.es/proposal-temporal/#sec-temporal.plaindatetime.prototype.valueof
 JS_DEFINE_NATIVE_FUNCTION(PlainDateTimePrototype::value_of)
 {

Userland/Libraries/LibJS/Runtime/Temporal/PlainDateTimePrototype.h

@@ -38,6 +38,7 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(days_in_year_getter);
     JS_DECLARE_NATIVE_FUNCTION(months_in_year_getter);
     JS_DECLARE_NATIVE_FUNCTION(in_leap_year_getter);
+    JS_DECLARE_NATIVE_FUNCTION(with_calendar);
     JS_DECLARE_NATIVE_FUNCTION(value_of);
     JS_DECLARE_NATIVE_FUNCTION(to_plain_date);
     JS_DECLARE_NATIVE_FUNCTION(get_iso_fields);

Userland/Libraries/LibJS/Tests/builtins/Temporal/PlainDateTime/PlainDateTime.prototype.withCalendar.js

@@ -0,0 +1,13 @@
+describe("correct behavior", () => {
+    test("length is 1", () => {
+        expect(Temporal.PlainDateTime.prototype.withCalendar).toHaveLength(1);
+    });
+
+    test("basic functionality", () => {
+        const calendar = { hello: "friends" };
+        const firstPlainDateTime = new Temporal.PlainDateTime(1, 2, 3);
+        expect(firstPlainDateTime.calendar).not.toBe(calendar);
+        const secondPlainDateTime = firstPlainDateTime.withCalendar(calendar);
+        expect(secondPlainDateTime.calendar).toBe(calendar);
+    });
+});