LibJS: Implement parsing of TemporalMonthDayString

Author: https://github.com/linusg
Commit: https://github.com/SerenityOS/serenity/commit/3ddab2f4fe3
Pull-request: https://github.com/SerenityOS/serenity/pull/10971
Reviewed-by: https://github.com/IdanHo ✅
Reviewed-by: https://github.com/alimpfard

Userland/Libraries/LibJS/Runtime/ErrorTypes.h

@@ -216,6 +216,7 @@
     M(TemporalInvalidEpochNanoseconds, "Invalid epoch nanoseconds value, must be in range -86400 * 10^17 to 86400 * 10^17")             \
     M(TemporalInvalidISODate, "Invalid ISO date")                                                                                       \
     M(TemporalInvalidMonthCode, "Invalid month code")                                                                                   \
+    M(TemporalInvalidMonthDayString, "Invalid month day string '{}'")                                                                   \
     M(TemporalInvalidOffsetNanosecondsValue, "Invalid offset nanoseconds value, must be in range -86400 * 10^9 to 86400 * 10^9")        \
     M(TemporalInvalidPlainDate, "Invalid plain date")                                                                                   \
     M(TemporalInvalidPlainDateTime, "Invalid plain date time")                                                                          \

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

@@ -1290,23 +1290,30 @@ ThrowCompletionOr<TemporalDuration> parse_temporal_duration_string(GlobalObject&
 }
 
 // 13.41 ParseTemporalMonthDayString ( isoString ), https://tc39.es/proposal-temporal/#sec-temporal-parsetemporalmonthdaystring
-ThrowCompletionOr<TemporalMonthDay> parse_temporal_month_day_string(GlobalObject& global_object, [[maybe_unused]] String const& iso_string)
+ThrowCompletionOr<TemporalMonthDay> parse_temporal_month_day_string(GlobalObject& global_object, String const& iso_string)
 {
+    auto& vm = global_object.vm();
+
     // 1. Assert: Type(isoString) is String.
 
     // 2. If isoString does not satisfy the syntax of a TemporalMonthDayString (see 13.33), then
-    // a. Throw a RangeError exception.
-    // TODO
+    auto parse_result = parse_iso8601(Production::TemporalMonthDayString, iso_string);
+    if (!parse_result.has_value()) {
+        // a. Throw a RangeError exception.
+        return vm.throw_completion<RangeError>(global_object, ErrorType::TemporalInvalidMonthDayString, iso_string);
+    }
 
     // 3. Let result be ? ParseISODateTime(isoString).
-    auto result = TRY(parse_iso_date_time(global_object, {}));
+    auto result = TRY(parse_iso_date_time(global_object, *parse_result));
 
     // 4. Let year be result.[[Year]].
     Optional<i32> year = result.year;
 
     // 5. If no part of isoString is produced by the DateYear production, then
-    // a. Set year to undefined.
-    // TODO (this is the case when TemporalMonthDayString is a DateSpecMonthDay)
+    if (!parse_result->date_year.has_value()) {
+        // a. Set year to undefined.
+        year = {};
+    }
 
     // 6. Return the Record { [[Year]]: year, [[Month]]: result.[[Month]], [[Day]]: result.[[Day]], [[Calendar]]: result.[[Calendar]] }.
     return TemporalMonthDay { .year = year, .month = result.month, .day = result.day, .calendar = move(result.calendar) };

Userland/Libraries/LibJS/Runtime/Temporal/ISO8601.cpp

@@ -210,6 +210,24 @@ bool ISO8601Parser::parse_date_day()
     return true;
 }
 
+// https://tc39.es/proposal-temporal/#prod-DateSpecMonthDay
+bool ISO8601Parser::parse_date_spec_month_day()
+{
+    // TwoDashes :
+    //     --
+    // DateSpecMonthDay :
+    //     TwoDashes[opt] DateMonth -[opt] DateDay
+    StateTransaction transaction { *this };
+    m_state.lexer.consume_specific("--"sv);
+    if (!parse_date_month())
+        return false;
+    m_state.lexer.consume_specific('-');
+    if (!parse_date_day())
+        return false;
+    transaction.commit();
+    return true;
+}
+
 // https://tc39.es/proposal-temporal/#prod-Date
 bool ISO8601Parser::parse_date()
 {
@@ -486,6 +504,18 @@ bool ISO8601Parser::parse_temporal_date_time_string()
     return parse_calendar_date_time();
 }
 
+// https://tc39.es/proposal-temporal/#prod-TemporalMonthDayString
+bool ISO8601Parser::parse_temporal_month_day_string()
+{
+    // TemporalMonthDayString :
+    //     DateSpecMonthDay
+    //     DateTime
+    // NOTE: Reverse order here because `DateSpecMonthDay` can be a subset of `DateTime`,
+    // so we'd not attempt to parse that but may not exhaust the input string.
+    return parse_date_time()
+        || parse_date_spec_month_day();
+}
+
 // https://tc39.es/proposal-temporal/#prod-TemporalTimeString
 bool ISO8601Parser::parse_temporal_time_string()
 {
@@ -503,6 +533,7 @@ bool ISO8601Parser::parse_temporal_time_string()
 #define JS_ENUMERATE_ISO8601_PRODUCTION_PARSERS                             \
     __JS_ENUMERATE(TemporalDateString, parse_temporal_date_string)          \
     __JS_ENUMERATE(TemporalDateTimeString, parse_temporal_date_time_string) \
+    __JS_ENUMERATE(TemporalMonthDayString, parse_temporal_month_day_string) \
     __JS_ENUMERATE(TemporalTimeString, parse_temporal_time_string)
 
 Optional<ParseResult> parse_iso8601(Production production, StringView input)

Userland/Libraries/LibJS/Runtime/Temporal/ISO8601.h

@@ -28,6 +28,7 @@ struct ParseResult {
 enum class Production {
     TemporalDateString,
     TemporalDateTimeString,
+    TemporalMonthDayString,
     TemporalTimeString,
 };
 
@@ -60,6 +61,7 @@ public:
     [[nodiscard]] bool parse_date_year();
     [[nodiscard]] bool parse_date_month();
     [[nodiscard]] bool parse_date_day();
+    [[nodiscard]] bool parse_date_spec_month_day();
     [[nodiscard]] bool parse_date();
     [[nodiscard]] bool parse_time_hour();
     [[nodiscard]] bool parse_time_minute();
@@ -80,6 +82,7 @@ public:
     [[nodiscard]] bool parse_calendar_date_time();
     [[nodiscard]] bool parse_temporal_date_string();
     [[nodiscard]] bool parse_temporal_date_time_string();
+    [[nodiscard]] bool parse_temporal_month_day_string();
     [[nodiscard]] bool parse_temporal_time_string();
 
 private:

Userland/Libraries/LibJS/Tests/builtins/Temporal/PlainMonthDay/PlainMonthDay.from.js

@@ -35,8 +35,14 @@ describe("correct behavior", () => {
         expect(plainMonthDay.day).toBe(6);
     });
 
+    test("from month day string", () => {
+        const plainMonthDay = Temporal.PlainMonthDay.from("--07-06");
+        expect(plainMonthDay.monthCode).toBe("M07");
+        expect(plainMonthDay.day).toBe(6);
+    });
+
     // Un-skip once ParseISODateTime, ToTemporalMonthDay & ParseTemporalMonthDayString are fully implemented
-    test.skip("PlainMonthDay string argument", () => {
+    test.skip("from date time string", () => {
         const plainMonthDay = Temporal.PlainMonthDay.from("2021-07-06T23:42:01Z");
         expect(plainMonthDay.monthCode).toBe("M07");
         expect(plainMonthDay.day).toBe(6);
@@ -55,4 +61,10 @@ describe("errors", () => {
             Temporal.PlainMonthDay.from({ day: 1 });
         }).toThrowWithMessage(TypeError, "Required property month is missing or undefined");
     });
+
+    test("invalid month day string", () => {
+        expect(() => {
+            Temporal.PlainMonthDay.from("foo");
+        }).toThrowWithMessage(RangeError, "Invalid month day string 'foo'");
+    });
 });