1 files changed, 29 insertions, 1 deletions
diff --git a/Userland/Libraries/LibUnicode/NumberFormat.h b/Userland/Libraries/LibUnicode/NumberFormat.h
index 2f3fcfac13..34b69f523a 100644
--- a/Userland/Libraries/LibUnicode/NumberFormat.h
+++ b/Userland/Libraries/LibUnicode/NumberFormat.h
@@ -79,7 +79,35 @@ Optional<NumberFormat> get_standard_number_system_format(StringView locale, Stri
 Vector<NumberFormat> get_compact_number_system_formats(StringView locale, StringView system, CompactNumberFormatType type);
 Vector<NumberFormat> get_unit_formats(StringView locale, StringView unit, Style style);
 
-Optional<NumberFormat> select_pattern_with_plurality(Vector<NumberFormat> const& formats, double number);
 Optional<String> augment_currency_format_pattern(StringView currency_display, StringView base_pattern);
 
+template<typename FormatType>
+Optional<FormatType> select_pattern_with_plurality(Vector<FormatType> const& formats, double number)
+{
+    // FIXME: This is a rather naive and locale-unaware implementation Unicode's TR-35 pluralization
+    //        rules: https://www.unicode.org/reports/tr35/tr35-numbers.html#Language_Plural_Rules
+    //        Once those rules are implemented for LibJS, we better use them instead.
+    auto find_plurality = [&](auto plurality) -> Optional<FormatType> {
+        if (auto it = formats.find_if([&](auto& patterns) { return patterns.plurality == plurality; }); it != formats.end())
+            return *it;
+        return {};
+    };
+
+    if (number == 0) {
+        if (auto patterns = find_plurality(FormatType::Plurality::Zero); patterns.has_value())
+            return patterns;
+    } else if (number == 1) {
+        if (auto patterns = find_plurality(FormatType::Plurality::One); patterns.has_value())
+            return patterns;
+    } else if (number == 2) {
+        if (auto patterns = find_plurality(FormatType::Plurality::Two); patterns.has_value())
+            return patterns;
+    } else if (number > 2) {
+        if (auto patterns = find_plurality(FormatType::Plurality::Many); patterns.has_value())
+            return patterns;
+    }
+
+    return find_plurality(FormatType::Plurality::Other);
+}
+
 }