LibJS: Implement Intl.Locale.prototype.variants

This is a normative change in the ECMA-402 spec. See:
e8c995a

Libraries/LibJS/Runtime/CommonPropertyNames.h

@@ -583,6 +583,7 @@ namespace JS {
     P(value)                                 \
     P(valueOf)                               \
     P(values)                                \
+    P(variants)                              \
     P(wait)                                  \
     P(waitAsync)                             \
     P(warn)                                  \

Libraries/LibJS/Runtime/Intl/Locale.cpp

@@ -43,6 +43,24 @@ Unicode::LocaleID const& Locale::locale_id() const
     return *m_cached_locale_id;
 }
 
+// 15.5.5 GetLocaleVariants ( locale ), https://tc39.es/ecma402/#sec-getlocalevariants
+Optional<String> get_locale_variants(Unicode::LocaleID const& locale)
+{
+    // 1. Let baseName be GetLocaleBaseName(locale).
+    auto const& base_name = locale.language_id;
+
+    // 2. NOTE: Each subtag in baseName that is preceded by "-" is either a unicode_script_subtag, unicode_region_subtag,
+    //    or unicode_variant_subtag, but any substring matched by unicode_variant_subtag is strictly longer than any
+    //    prefix thereof which could also be matched by one of the other productions.
+
+    // 3. Let variants be the longest suffix of baseName that starts with a "-" followed by a substring that is matched
+    //    by the unicode_variant_subtag Unicode locale nonterminal. If there is no such suffix, return undefined.
+    // 4. Return the substring of variants from 1.
+    if (base_name.variants.is_empty())
+        return {};
+    return MUST(String::join("-"sv, base_name.variants));
+}
+
 // 1.1.1 CreateArrayFromListOrRestricted ( list , restricted )
 static GC::Ref<Array> create_array_from_list_or_restricted(VM& vm, Vector<String> list, Optional<String> restricted)
 {

Libraries/LibJS/Runtime/Intl/Locale.h

@@ -91,6 +91,8 @@ struct WeekInfo {
     Vector<u8> weekend;    // [[Weekend]]
 };
 
+Optional<String> get_locale_variants(Unicode::LocaleID const&);
+
 GC::Ref<Array> calendars_of_locale(VM&, Locale const&);
 GC::Ref<Array> collations_of_locale(VM&, Locale const& locale);
 GC::Ref<Array> hour_cycles_of_locale(VM&, Locale const& locale);

Libraries/LibJS/Runtime/Intl/LocaleConstructor.cpp

@@ -66,25 +66,61 @@ static ThrowCompletionOr<String> update_language_id(VM& vm, StringView tag, Obje
     //     a. If region cannot be matched by the unicode_region_subtag Unicode locale nonterminal, throw a RangeError exception.
     auto region = TRY(get_string_option(vm, options, vm.names.region, Unicode::is_unicode_region_subtag, {}, base_name.region));
 
-    // 8. Let allExtensions be the suffix of tag following baseName.
+    // 8. Let variants be ? GetOption(options, "variants", STRING, EMPTY, GetLocaleVariants(baseName)).
+    auto variants = TRY(get_string_option(vm, options, vm.names.variants, nullptr, {}, get_locale_variants(*locale_id)));
+    Vector<String> variant_subtags;
+
+    // 9. If variants is not undefined, then
+    if (variants.has_value()) {
+        // a. If variants is the empty String, throw a RangeError exception.
+        if (variants->is_empty())
+            return vm.throw_completion<RangeError>(ErrorType::OptionIsNotValidValue, *variants, vm.names.variants);
+
+        // b. Let lowerVariants be the ASCII-lowercase of variants.
+        auto lower_variants = variants->to_ascii_lowercase();
+
+        // c. Let variantSubtags be StringSplitToList(lowerVariants, "-").
+        variant_subtags = MUST(lower_variants.split('-', SplitBehavior::KeepEmpty));
+
+        HashTable<String> seen_variants;
+        bool has_duplicate_variant = false;
+
+        // d. For each element variant of variantSubtags, do
+        for (auto const& variant : variant_subtags) {
+            has_duplicate_variant |= seen_variants.set(variant) != HashSetResult::InsertedNewEntry;
+
+            // i. If variant cannot be matched by the unicode_variant_subtag Unicode locale nonterminal, throw a RangeError exception.
+            if (!Unicode::is_unicode_variant_subtag(variant))
+                return vm.throw_completion<RangeError>(ErrorType::OptionIsNotValidValue, *variants, vm.names.variants);
+        }
+
+        // e. If variantSubtags contains any duplicate elements, throw a RangeError exception.
+        if (has_duplicate_variant)
+            return vm.throw_completion<RangeError>(ErrorType::OptionIsNotValidValue, *variants, vm.names.variants);
+    }
+
+    // 10. Let allExtensions be the suffix of tag following baseName.
     auto& extensions = locale_id->extensions;
     auto& private_use_extensions = locale_id->private_use_extensions;
 
-    // 9. Let newTag be language.
+    // 11. Let newTag be language.
     Unicode::LocaleID new_tag;
     new_tag.language_id.language = move(language);
 
-    // 10. If script is not undefined, set newTag to the string-concatenation of newTag, "-", and script.
+    // 12. If script is not undefined, set newTag to the string-concatenation of newTag, "-", and script.
     new_tag.language_id.script = move(script);
 
-    // 11. If region is not undefined, set newTag to the string-concatenation of newTag, "-", and region.
+    // 13. If region is not undefined, set newTag to the string-concatenation of newTag, "-", and region.
     new_tag.language_id.region = move(region);
 
-    // 12. Set newTag to the string-concatenation of newTag and allExtensions.
+    // 14. If variants is not undefined, set newTag to the string-concatenation of newTag, "-", and variants.
+    new_tag.language_id.variants = move(variant_subtags);
+
+    // 15. Set newTag to the string-concatenation of newTag and allExtensions.
     new_tag.extensions = move(extensions);
     new_tag.private_use_extensions = move(private_use_extensions);
 
-    // 13. Return newTag.
+    // 16. Return newTag.
     return new_tag.to_string();
 }
 

Libraries/LibJS/Runtime/Intl/LocalePrototype.cpp

@@ -39,7 +39,7 @@ void LocalePrototype::initialize(Realm& realm)
     define_native_function(realm, vm.names.getTextInfo, get_text_info, 0, attr);
     define_native_function(realm, vm.names.getWeekInfo, get_week_info, 0, attr);
 
-    // 15.3.15 Intl.Locale.prototype [ %Symbol.toStringTag% ], https://tc39.es/ecma402/#sec-intl.locale.prototype-%symbol.tostringtag%
+    // 15.3.16 Intl.Locale.prototype [ %Symbol.toStringTag% ], https://tc39.es/ecma402/#sec-intl.locale.prototype-%symbol.tostringtag%
     define_direct_property(vm.well_known_symbol_to_string_tag(), PrimitiveString::create(vm, "Intl.Locale"_string), Attribute::Configurable);
 
     define_native_accessor(realm, vm.names.baseName, base_name, {}, Attribute::Configurable);
@@ -53,6 +53,7 @@ void LocalePrototype::initialize(Realm& realm)
     define_native_accessor(realm, vm.names.numeric, numeric, {}, Attribute::Configurable);
     define_native_accessor(realm, vm.names.region, region, {}, Attribute::Configurable);
     define_native_accessor(realm, vm.names.script, script, {}, Attribute::Configurable);
+    define_native_accessor(realm, vm.names.variants, variants, {}, Attribute::Configurable);
 }
 
 // 15.3.2 get Intl.Locale.prototype.baseName, https://tc39.es/ecma402/#sec-Intl.Locale.prototype.baseName
@@ -182,6 +183,19 @@ JS_DEFINE_NATIVE_FUNCTION(LocalePrototype::to_string)
     return PrimitiveString::create(vm, locale_object->locale());
 }
 
+// 15.3.15 get Intl.Locale.prototype.variants, https://tc39.es/ecma402/#sec-Intl.Locale.prototype.variants
+JS_DEFINE_NATIVE_FUNCTION(LocalePrototype::variants)
+{
+    // 1. Let loc be the this value.
+    // 2. Perform ? RequireInternalSlot(loc, [[InitializedLocale]]).
+    auto locale_object = TRY(typed_this_object(vm));
+
+    // 3. Return GetLocaleVariants(loc.[[Locale]]).
+    if (auto variants = get_locale_variants(locale_object->locale_id()); variants.has_value())
+        return PrimitiveString::create(vm, variants.release_value());
+    return js_undefined();
+}
+
 #define JS_ENUMERATE_LOCALE_INFO_PROPERTIES \
     __JS_ENUMERATE(calendars)               \
     __JS_ENUMERATE(collations)              \

Libraries/LibJS/Runtime/Intl/LocalePrototype.h

@@ -37,6 +37,7 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(numeric);
     JS_DECLARE_NATIVE_FUNCTION(region);
     JS_DECLARE_NATIVE_FUNCTION(script);
+    JS_DECLARE_NATIVE_FUNCTION(variants);
     JS_DECLARE_NATIVE_FUNCTION(get_calendars);
     JS_DECLARE_NATIVE_FUNCTION(get_collations);
     JS_DECLARE_NATIVE_FUNCTION(get_hour_cycles);

Libraries/LibJS/Tests/builtins/Intl/Locale/Locale.prototype.variants.js

@@ -0,0 +1,44 @@
+describe("errors", () => {
+    test("called on non-Locale object", () => {
+        expect(() => {
+            Intl.Locale.prototype.variants;
+        }).toThrowWithMessage(TypeError, "Not an object of type Intl.Locale");
+    });
+
+    test("duplicate variants", () => {
+        expect(() => {
+            new Intl.Locale("en-abcde-abcde");
+        }).toThrowWithMessage(
+            RangeError,
+            "en-abcde-abcde is not a structurally valid language tag"
+        );
+
+        expect(() => {
+            new Intl.Locale("en", { variants: "abcde-abcde" });
+        }).toThrowWithMessage(RangeError, "abcde-abcde is not a valid value for option variants");
+    });
+
+    test("invalid variant", () => {
+        expect(() => {
+            new Intl.Locale("en-a");
+        }).toThrowWithMessage(RangeError, "en-a is not a structurally valid language tag");
+
+        expect(() => {
+            new Intl.Locale("en", { variants: "a" });
+        }).toThrowWithMessage(RangeError, "a is not a valid value for option variants");
+
+        expect(() => {
+            new Intl.Locale("en", { variants: "-" });
+        }).toThrowWithMessage(RangeError, "- is not a valid value for option variants");
+    });
+});
+
+describe("normal behavior", () => {
+    test("basic functionality", () => {
+        expect(new Intl.Locale("en").variants).toBeUndefined();
+        expect(new Intl.Locale("en-abcde").variants).toBe("abcde");
+        expect(new Intl.Locale("en-1234-abcde").variants).toBe("1234-abcde");
+        expect(new Intl.Locale("en", { variants: "abcde" }).variants).toBe("abcde");
+        expect(new Intl.Locale("en", { variants: "1234-abcde" }).variants).toBe("1234-abcde");
+    });
+});