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

a

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

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2021, Linus Groh <linusg@serenityos.org>
+ * Copyright (c) 2021, Luke Wilde <lukew@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -40,6 +41,7 @@ void PlainTimePrototype::initialize(GlobalObject& global_object)
 
     u8 attr = Attribute::Writable | Attribute::Configurable;
     define_native_function(vm.names.add, add, 1, attr);
+    define_native_function(vm.names.subtract, subtract, 1, attr);
     define_native_function(vm.names.with, with, 1, attr);
     define_native_function(vm.names.equals, equals, 1, attr);
     define_native_function(vm.names.toPlainDateTime, to_plain_date_time, 1, attr);
@@ -149,6 +151,28 @@ JS_DEFINE_NATIVE_FUNCTION(PlainTimePrototype::add)
     return TRY(create_temporal_time(global_object, result.hour, result.minute, result.second, result.millisecond, result.microsecond, result.nanosecond));
 }
 
+// 4.3.11 Temporal.PlainTime.prototype.subtract ( temporalDurationLike ), https://tc39.es/proposal-temporal/#sec-temporal.plaintime.prototype.subtract
+JS_DEFINE_NATIVE_FUNCTION(PlainTimePrototype::subtract)
+{
+    auto temporal_duration_like = vm.argument(0);
+
+    // 1. Let temporalTime be the this value.
+    // 2. Perform ? RequireInternalSlot(temporalTime, [[InitializedTemporalTime]]).
+    auto* temporal_time = TRY(typed_this_object(global_object));
+
+    // 3. Let duration be ? ToLimitedTemporalDuration(temporalDurationLike, « »).
+    auto duration = TRY(to_limited_temporal_duration(global_object, temporal_duration_like, {}));
+
+    // 4. Let result be ! AddTime(temporalTime.[[ISOHour]], temporalTime.[[ISOMinute]], temporalTime.[[ISOSecond]], temporalTime.[[ISOMillisecond]], temporalTime.[[ISOMicrosecond]], temporalTime.[[ISONanosecond]], −duration.[[Hours]], −duration.[[Minutes]], −duration.[[Seconds]], −duration.[[Milliseconds]], −duration.[[Microseconds]], −duration.[[Nanoseconds]]).
+    auto result = add_time(temporal_time->iso_hour(), temporal_time->iso_minute(), temporal_time->iso_second(), temporal_time->iso_millisecond(), temporal_time->iso_microsecond(), temporal_time->iso_nanosecond(), -duration.hours, -duration.minutes, -duration.seconds, -duration.milliseconds, -duration.microseconds, -duration.nanoseconds);
+
+    // 5. 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));
+
+    // 6. Return ? CreateTemporalTime(result.[[Hour]], result.[[Minute]], result.[[Second]], result.[[Millisecond]], result.[[Microsecond]], result.[[Nanosecond]]).
+    return TRY(create_temporal_time(global_object, result.hour, result.minute, result.second, result.millisecond, result.microsecond, result.nanosecond));
+}
+
 // 4.3.12 Temporal.PlainTime.prototype.with ( temporalTimeLike [ , options ] ), https://tc39.es/proposal-temporal/#sec-temporal.plaintime.prototype.with
 JS_DEFINE_NATIVE_FUNCTION(PlainTimePrototype::with)
 {

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

@@ -28,6 +28,7 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(microsecond_getter);
     JS_DECLARE_NATIVE_FUNCTION(nanosecond_getter);
     JS_DECLARE_NATIVE_FUNCTION(add);
+    JS_DECLARE_NATIVE_FUNCTION(subtract);
     JS_DECLARE_NATIVE_FUNCTION(with);
     JS_DECLARE_NATIVE_FUNCTION(equals);
     JS_DECLARE_NATIVE_FUNCTION(to_plain_date_time);

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

@@ -0,0 +1,27 @@
+describe("correct behavior", () => {
+    test("length is 1", () => {
+        expect(Temporal.PlainTime.prototype.subtract).toHaveLength(1);
+    });
+
+    test("basic functionality", () => {
+        const plainTime = new Temporal.PlainTime(1, 2, 3, 4, 5, 6);
+        const duration = new Temporal.Duration(2021, 10, 1, 1, 0, 1, 2, 3, 4, 5);
+        const result = plainTime.subtract(duration);
+        expect(result.hour).toBe(1);
+        expect(result.minute).toBe(1);
+        expect(result.second).toBe(1);
+        expect(result.millisecond).toBe(1);
+        expect(result.microsecond).toBe(1);
+        expect(result.nanosecond).toBe(1);
+    });
+});
+
+describe("errors", () => {
+    test("invalid duration-like", () => {
+        const plainTime = new Temporal.PlainTime(1, 1, 1, 1, 1, 1);
+        const invalidDuration = { foo: 1, bar: 2 };
+        expect(() => {
+            plainTime.subtract(invalidDuration);
+        }).toThrowWithMessage(TypeError, "Invalid duration-like object");
+    });
+});