LibJS+LibUnicode: Don't remove {currency} keys in GetNumberFormatPattern

In order to implement Intl.NumberFormat.prototype.formatToParts, do not
replace {currency} keys in the format pattern before ECMA-402 tells us
to. Otherwise, the array return by formatToParts will not contain the
expected currency key.

Early replacement was done to avoid resolving the currency display more
than once, as it involves a couple of round trips to search through
LibUnicode data. So this adds a non-standard method to NumberFormat to
do this resolution and cache the result.

Another side effect of this change is that LibUnicode must replace unit
format patterns of the form "{0} {1}" during code generation. These were
previously skipped during code generation because LibJS would just
replace the keys with the currency display at runtime. But now that the
currency display injection is delayed, any {0} or {1} keys in the format
pattern will cause PartitionNumberPattern to abort.

Meta/Lagom/Tools/CodeGenerators/LibUnicode/GenerateUnicodeNumberFormat.cpp

@@ -79,24 +79,23 @@ struct UnicodeLocaleData {
     Vector<String> numeric_symbols;
 };
 
-static void parse_number_pattern(String pattern, UnicodeLocaleData& locale_data, NumberFormat& format, bool is_unit_pattern = false)
+static void parse_number_pattern(String pattern, UnicodeLocaleData& locale_data, NumberFormat& format)
 {
     // https://unicode.org/reports/tr35/tr35-numbers.html#Number_Format_Patterns
     // https://cldr.unicode.org/translation/number-currency-formats/number-and-currency-patterns
     auto replace_patterns = [&](String pattern) {
-        if (is_unit_pattern) {
-            // Skip parsing unit patterns, which are of the form "{0} {1}", and do not contain any
-            // of the replacement patterns below.
-            return pattern;
-        }
-
         static HashMap<StringView, StringView> replacements = {
+            { "{0}"sv, "{number}"sv },
+            { "{1}"sv, "{currency}"sv },
             { "%"sv, "{percentSign}"sv },
             { "+"sv, "{plusSign}"sv },
             { "-"sv, "{minusSign}"sv },
             { "¤"sv, "{currency}"sv }, // U+00A4 Currency Sign
         };
 
+        for (auto const& replacement : replacements)
+            pattern = pattern.replace(replacement.key, replacement.value, true);
+
         if (auto start_number_index = pattern.find_any_of("#0"sv, String::SearchDirection::Forward); start_number_index.has_value()) {
             auto end_number_index = *start_number_index + 1;
 
@@ -111,9 +110,6 @@ static void parse_number_pattern(String pattern, UnicodeLocaleData& locale_data,
                 pattern.substring_view(end_number_index));
         }
 
-        for (auto const& replacement : replacements)
-            pattern = pattern.replace(replacement.key, replacement.value, true);
-
         return pattern;
     };
 
@@ -173,18 +169,16 @@ static void parse_number_systems(String locale_numbers_path, UnicodeLocaleData&
                 return;
 
             NumberFormat format {};
-            bool is_unit_pattern = false;
 
             if (auto type = split_key[0].template to_uint<u64>(); type.has_value()) {
                 VERIFY(*type % 10 == 0);
                 format.magnitude = static_cast<u8>(log10(*type));
             } else {
                 VERIFY(split_key[0] == "unitPattern"sv);
-                is_unit_pattern = true;
             }
 
             format.plurality = NumberFormat::plurality_from_string(split_key[2]);
-            parse_number_pattern(value.as_string(), locale_data, format, is_unit_pattern);
+            parse_number_pattern(value.as_string(), locale_data, format);
 
             result.append(move(format));
         });

Userland/Libraries/LibJS/Runtime/Intl/NumberFormat.cpp

@@ -68,6 +68,8 @@ StringView NumberFormat::style_string() const
 
 void NumberFormat::set_currency_display(StringView currency_display)
 {
+    m_resolved_currency_display.clear();
+
     if (currency_display == "code"sv)
         m_currency_display = CurrencyDisplay::Code;
     else if (currency_display == "symbol"sv)
@@ -80,6 +82,34 @@ void NumberFormat::set_currency_display(StringView currency_display)
         VERIFY_NOT_REACHED();
 }
 
+StringView NumberFormat::resolve_currency_display()
+{
+    if (m_resolved_currency_display.has_value())
+        return *m_resolved_currency_display;
+
+    switch (currency_display()) {
+    case NumberFormat::CurrencyDisplay::Code:
+        m_resolved_currency_display = currency();
+        break;
+    case NumberFormat::CurrencyDisplay::Symbol:
+        m_resolved_currency_display = Unicode::get_locale_currency_mapping(data_locale(), currency(), Unicode::Style::Short);
+        break;
+    case NumberFormat::CurrencyDisplay::NarrowSymbol:
+        m_resolved_currency_display = Unicode::get_locale_currency_mapping(data_locale(), currency(), Unicode::Style::Narrow);
+        break;
+    case NumberFormat::CurrencyDisplay::Name:
+        m_resolved_currency_display = Unicode::get_locale_currency_mapping(data_locale(), currency(), Unicode::Style::Numeric);
+        break;
+    default:
+        VERIFY_NOT_REACHED();
+    }
+
+    if (!m_resolved_currency_display.has_value())
+        m_resolved_currency_display = currency();
+
+    return *m_resolved_currency_display;
+}
+
 StringView NumberFormat::currency_display_string() const
 {
     VERIFY(m_currency_display.has_value());
@@ -664,8 +694,12 @@ Vector<PatternPartition> partition_number_pattern(NumberFormat& number_format, d
         // j. Else if p is equal to "currencyPrefix" and numberFormat.[[Style]] is "currency", then
         // k. Else if p is equal to "currencySuffix" and numberFormat.[[Style]] is "currency", then
         //
-        // Note: Our implementation formats currency codes during GetNumberFormatPattern so that we
+        // Note: Our implementation manipulates the format string to inject/remove spacing around the
-        //       do not have to do currency display / plurality lookups more than once.
+        //       currency code during GetNumberFormatPattern so that we do not have to do currency
+        //       display / plurality lookups more than once.
+        else if ((part == "currency"sv) && (number_format.style() == NumberFormat::Style::Currency)) {
+            result.append({ "currency"sv, number_format.resolve_currency_display() });
+        }
 
         // l. Else,
         else {
@@ -1323,33 +1357,9 @@ Optional<Variant<StringView, String>> get_number_format_pattern(NumberFormat& nu
     // we might need to mutate the format pattern to inject a space between the currency display and
     // the currency number.
     if (number_format.style() == NumberFormat::Style::Currency) {
-        if (number_format.currency_display() == NumberFormat::CurrencyDisplay::Name) {
+        auto modified_pattern = Unicode::augment_currency_format_pattern(number_format.resolve_currency_display(), pattern);
-            auto maybe_currency_display = Unicode::get_locale_currency_mapping(number_format.data_locale(), number_format.currency(), Unicode::Style::Numeric);
+        if (modified_pattern.has_value())
-            auto currency_display = maybe_currency_display.value_or(number_format.currency());
+            return modified_pattern.release_value();
-
-            return pattern.replace("{0}"sv, "{number}"sv).replace("{1}"sv, currency_display);
-        }
-
-        Optional<StringView> currency_display;
-
-        switch (number_format.currency_display()) {
-        case NumberFormat::CurrencyDisplay::Code:
-            currency_display = number_format.currency();
-            break;
-        case NumberFormat::CurrencyDisplay::Symbol:
-            currency_display = Unicode::get_locale_currency_mapping(number_format.data_locale(), number_format.currency(), Unicode::Style::Short);
-            break;
-        case NumberFormat::CurrencyDisplay::NarrowSymbol:
-            currency_display = Unicode::get_locale_currency_mapping(number_format.data_locale(), number_format.currency(), Unicode::Style::Narrow);
-            break;
-        default:
-            VERIFY_NOT_REACHED();
-        }
-
-        if (!currency_display.has_value())
-            currency_display = number_format.currency();
-
-        return Unicode::create_currency_format_pattern(*currency_display, pattern);
     }
 
     // 16. Return pattern.

Userland/Libraries/LibJS/Runtime/Intl/NumberFormat.h

@@ -97,6 +97,7 @@ public:
     CurrencyDisplay currency_display() const { return *m_currency_display; }
     StringView currency_display_string() const;
     void set_currency_display(StringView currency_display);
+    StringView resolve_currency_display();
 
     bool has_currency_sign() const { return m_currency_sign.has_value(); }
     CurrencySign currency_sign() const { return *m_currency_sign; }
@@ -177,6 +178,9 @@ private:
     Optional<CompactDisplay> m_compact_display {};          // [[CompactDisplay]]
     SignDisplay m_sign_display { SignDisplay::Invalid };    // [[SignDisplay]]
     NativeFunction* m_bound_format { nullptr };             // [[BoundFormat]]
+
+    // Non-standard. Stores the resolved currency display string based on [[Locale]], [[Currency]], and [[CurrencyDisplay]].
+    Optional<StringView> m_resolved_currency_display;
 };
 
 struct FormatResult {

Userland/Libraries/LibUnicode/Locale.cpp

@@ -997,7 +997,7 @@ Optional<NumberFormat> select_currency_unit_pattern(StringView locale, StringVie
 }
 
 // https://www.unicode.org/reports/tr35/tr35-numbers.html#Currencies
-String create_currency_format_pattern(StringView currency_display, StringView base_pattern)
+Optional<String> augment_currency_format_pattern([[maybe_unused]] StringView currency_display, [[maybe_unused]] StringView base_pattern)
 {
 #if ENABLE_UNICODE_DATA
     constexpr auto number_key = "{number}"sv;
@@ -1011,7 +1011,7 @@ String create_currency_format_pattern(StringView currency_display, StringView ba
     VERIFY(currency_index.has_value());
 
     Utf8View utf8_currency_display { currency_display };
-    Optional<String> currency_display_with_spacing;
+    Optional<String> currency_key_with_spacing;
 
     auto last_code_point = [](StringView string) {
         Utf8View utf8_string { string };
@@ -1030,7 +1030,7 @@ String create_currency_format_pattern(StringView currency_display, StringView ba
             u32 first_currency_code_point = *utf8_currency_display.begin();
 
             if (!code_point_has_general_category(first_currency_code_point, GeneralCategory::Symbol))
-                currency_display_with_spacing = String::formatted("{}{}", spacing, currency_display);
+                currency_key_with_spacing = String::formatted("{}{}", spacing, currency_key);
         }
     } else {
         u32 last_pattern_code_point = last_code_point(base_pattern.substring_view(0, *number_index));
@@ -1039,15 +1039,15 @@ String create_currency_format_pattern(StringView currency_display, StringView ba
             u32 last_currency_code_point = last_code_point(currency_display);
 
             if (!code_point_has_general_category(last_currency_code_point, GeneralCategory::Symbol))
-                currency_display_with_spacing = String::formatted("{}{}", currency_display, spacing);
+                currency_key_with_spacing = String::formatted("{}{}", currency_key, spacing);
         }
     }
 
-    if (currency_display_with_spacing.has_value())
+    if (currency_key_with_spacing.has_value())
-        return base_pattern.replace(currency_key, *currency_display_with_spacing);
+        return base_pattern.replace(currency_key, *currency_key_with_spacing);
 #endif
 
-    return base_pattern.replace(currency_key, currency_display);
+    return {};
 }
 
 String LanguageID::to_string() const

Userland/Libraries/LibUnicode/Locale.h

@@ -196,6 +196,6 @@ Optional<LanguageID> remove_likely_subtags(LanguageID const& language_id);
 String resolve_most_likely_territory(LanguageID const& language_id, StringView territory_alias);
 
 Optional<NumberFormat> select_currency_unit_pattern(StringView locale, StringView system, double number);
-String create_currency_format_pattern(StringView currency_display, StringView base_pattern);
+Optional<String> augment_currency_format_pattern(StringView currency_display, StringView base_pattern);
 
 }