LibJS: Implement Temporal.PlainDateTime.prototype.subtract()

Author: https://github.com/linusg
Commit: https://github.com/SerenityOS/serenity/commit/07b0aded99f
Pull-request: https://github.com/SerenityOS/serenity/pull/10757
Reviewed-by: https://github.com/IdanHo ✅

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

@@ -58,6 +58,7 @@ void PlainDateTimePrototype::initialize(GlobalObject& global_object)
     define_native_function(vm.names.withPlainDate, with_plain_date, 1, attr);
     define_native_function(vm.names.withCalendar, with_calendar, 1, attr);
     define_native_function(vm.names.add, add, 1, attr);
+    define_native_function(vm.names.subtract, subtract, 1, attr);
     define_native_function(vm.names.equals, equals, 1, attr);
     define_native_function(vm.names.valueOf, value_of, 0, attr);
     define_native_function(vm.names.toPlainDate, to_plain_date, 0, attr);
@@ -417,6 +418,32 @@ JS_DEFINE_NATIVE_FUNCTION(PlainDateTimePrototype::add)
     return TRY(create_temporal_date_time(global_object, result.year, result.month, result.day, result.hour, result.minute, result.second, result.millisecond, result.microsecond, result.nanosecond, date_time->calendar()));
 }
 
+// 5.3.27 Temporal.PlainDateTime.prototype.subtract ( temporalDurationLike [ , options ] ), https://tc39.es/proposal-temporal/#sec-temporal.plaindatetime.prototype.subtract
+JS_DEFINE_NATIVE_FUNCTION(PlainDateTimePrototype::subtract)
+{
+    // 1. Let dateTime be the this value.
+    // 2. Perform ? RequireInternalSlot(dateTime, [[InitializedTemporalDateTime]]).
+    auto* date_time = TRY(typed_this_object(global_object));
+
+    // 3. Let duration be ? ToLimitedTemporalDuration(temporalDurationLike, « »).
+    auto duration = TRY(to_limited_temporal_duration(global_object, vm.argument(0), {}));
+
+    // 4. Set options to ? GetOptionsObject(options).
+    auto* options = TRY(get_options_object(global_object, vm.argument(1)));
+
+    // 5. Let result be ? AddDateTime(dateTime.[[ISOYear]], dateTime.[[ISOMonth]], dateTime.[[ISODay]], dateTime.[[ISOHour]], dateTime.[[ISOMinute]], dateTime.[[ISOSecond]], dateTime.[[ISOMillisecond]], dateTime.[[ISOMicrosecond]], dateTime.[[ISONanosecond]], dateTime.[[Calendar]], −duration.[[Years]], −duration.[[Months]], −duration.[[Weeks]], −duration.[[Days]], −duration.[[Hours]], −duration.[[Minutes]], −duration.[[Seconds]], −duration.[[Milliseconds]], −duration.[[Microseconds]], −duration.[[Nanoseconds]], options).
+    auto result = TRY(add_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(), date_time->calendar(), -duration.years, -duration.months, -duration.weeks, -duration.days, -duration.hours, -duration.minutes, -duration.seconds, -duration.milliseconds, -duration.microseconds, -duration.nanoseconds, options));
+
+    // 6. Assert: ! IsValidISODate(result.[[Year]], result.[[Month]], result.[[Day]]) is true.
+    VERIFY(is_valid_iso_date(result.year, result.month, result.day));
+
+    // 7. Assert: ! IsValidTime(result.[[Hour]], result.[[Minute]], result.[[Second]], result.[[Millisecond]], result.[[Microsecond]], result.[[Nanosecond]]) is true.
+    VERIFY(is_valid_time(result.hour, result.minute, result.second, result.millisecond, result.microsecond, result.nanosecond));
+
+    // 8. Return ? CreateTemporalDateTime(result.[[Year]], result.[[Month]], result.[[Day]], result.[[Hour]], result.[[Minute]], result.[[Second]], result.[[Millisecond]], result.[[Microsecond]], result.[[Nanosecond]], dateTime.[[Calendar]]).
+    return TRY(create_temporal_date_time(global_object, result.year, result.month, result.day, result.hour, result.minute, result.second, result.millisecond, result.microsecond, result.nanosecond, date_time->calendar()));
+}
+
 // 5.3.31 Temporal.PlainDateTime.prototype.equals ( other ), https://tc39.es/proposal-temporal/#sec-temporal.plaindatetime.prototype.equals
 JS_DEFINE_NATIVE_FUNCTION(PlainDateTimePrototype::equals)
 {

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

@@ -45,6 +45,7 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(with_plain_date);
     JS_DECLARE_NATIVE_FUNCTION(with_calendar);
     JS_DECLARE_NATIVE_FUNCTION(add);
+    JS_DECLARE_NATIVE_FUNCTION(subtract);
     JS_DECLARE_NATIVE_FUNCTION(equals);
     JS_DECLARE_NATIVE_FUNCTION(value_of);
     JS_DECLARE_NATIVE_FUNCTION(to_plain_date);

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

@@ -0,0 +1,19 @@
+describe("correct behavior", () => {
+    test("length is 1", () => {
+        expect(Temporal.PlainDateTime.prototype.subtract).toHaveLength(1);
+    });
+
+    test("basic functionality", () => {
+        const plainDateTime = new Temporal.PlainDateTime(2021, 7, 6, 18, 14, 47);
+        const result = plainDateTime.subtract(new Temporal.Duration(51, 6, 0, 5, 18, 14, 47));
+        expect(result.equals(new Temporal.PlainDateTime(1970, 1, 1)));
+    });
+});
+
+describe("errors", () => {
+    test("this value must be a Temporal.PlainDateTime object", () => {
+        expect(() => {
+            Temporal.PlainDateTime.prototype.subtract.call("foo");
+        }).toThrowWithMessage(TypeError, "Not an object of type Temporal.PlainDateTime");
+    });
+});