LibUnicode: Parse and generate available candidate format patterns

These formats are used by ECMA-402 when neither a date nor time style is
specified. In that case, these patterns are searched for a best match.

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

@@ -38,6 +38,7 @@ struct Calendar {
     CalendarFormat date_formats {};
     CalendarFormat time_formats {};
     CalendarFormat date_time_formats {};
+    Vector<CalendarPattern> available_formats {};
 };
 
 struct Locale {
@@ -53,6 +54,8 @@ struct UnicodeLocaleData {
         // FIXME: Aliases should come from BCP47. See: https://unicode-org.atlassian.net/browse/CLDR-15158
         { "gregorian"sv, "gregory"sv },
     };
+
+    size_t max_available_formats_size { 0 };
 };
 
 static void parse_date_time_pattern(CalendarPattern& format, String pattern, UnicodeLocaleData& locale_data)
@@ -114,6 +117,15 @@ static ErrorOr<void> parse_calendars(String locale_calendars_path, UnicodeLocale
 
         auto const& date_time_formats_object = value.as_object().get("dateTimeFormats"sv);
         parse_patterns(calendar.date_time_formats, date_time_formats_object.as_object());
+
+        auto const& available_formats = date_time_formats_object.as_object().get("availableFormats"sv);
+        available_formats.as_object().for_each_member([&](auto const&, JsonValue const& pattern) {
+            CalendarPattern format {};
+            parse_date_time_pattern(format, pattern.as_string(), locale_data);
+            calendar.available_formats.append(move(format));
+        });
+
+        locale_data.max_available_formats_size = max(locale_data.max_available_formats_size, calendar.available_formats.size());
     });
 
     return {};
@@ -181,6 +193,7 @@ Optional<Calendar> calendar_from_string(StringView calendar);
 Optional<Unicode::CalendarFormat> get_calendar_date_format(StringView locale, StringView calendar);
 Optional<Unicode::CalendarFormat> get_calendar_time_format(StringView locale, StringView calendar);
 Optional<Unicode::CalendarFormat> get_calendar_date_time_format(StringView locale, StringView calendar);
+Vector<Unicode::CalendarPattern> get_calendar_available_formats(StringView locale, StringView calendar);
 
 }
 
@@ -195,6 +208,7 @@ static void generate_unicode_locale_implementation(Core::File& file, UnicodeLoca
     StringBuilder builder;
     SourceGenerator generator { builder };
     generator.set("string_index_type"sv, s_string_index_type);
+    generator.set("available_formats_size"sv, String::number(locale_data.max_available_formats_size));
 
     generator.append(R"~~~(
 #include <AK/Array.h>
@@ -242,6 +256,8 @@ struct CalendarData {
     CalendarFormat date_formats {};
     CalendarFormat time_formats {};
     CalendarFormat date_time_formats {};
+    Array<CalendarPattern, @available_formats_size@> available_formats {};
+    size_t available_formats_size { 0 };
 };
 )~~~");
 
@@ -281,7 +297,15 @@ static constexpr Array<CalendarData, @size@> @name@ { {)~~~");
             append_calendar_format(calendar.time_formats);
             generator.append(" ");
             append_calendar_format(calendar.date_time_formats);
-            generator.append(" },");
+            generator.append(" {{");
+
+            for (auto const& format : calendar.available_formats) {
+                generator.append(" ");
+                append_calendar_pattern(format);
+            }
+
+            generator.set("size", String::number(calendar.available_formats.size()));
+            generator.append(" }}, @size@ },");
         }
 
         generator.append(R"~~~(
@@ -344,6 +368,20 @@ Optional<Unicode::CalendarFormat> get_calendar_date_time_format(StringView local
     return {};
 }
 
+Vector<Unicode::CalendarPattern> get_calendar_available_formats(StringView locale, StringView calendar)
+{
+    Vector<Unicode::CalendarPattern> result {};
+
+    if (auto const* data = find_calendar_data(locale, calendar); data != nullptr) {
+        result.ensure_capacity(data->available_formats_size);
+
+        for (size_t i = 0; i < data->available_formats_size; ++i)
+            result.unchecked_append(data->available_formats[i].to_unicode_calendar_pattern());
+    }
+
+    return result;
+}
+
 }
 )~~~");
 

Userland/Libraries/LibUnicode/DateTimeFormat.cpp

@@ -63,4 +63,13 @@ Optional<CalendarFormat> get_calendar_format([[maybe_unused]] StringView locale,
 #endif
 }
 
+Vector<CalendarPattern> get_calendar_available_formats([[maybe_unused]] StringView locale, [[maybe_unused]] StringView calendar)
+{
+#if ENABLE_UNICODE_DATA
+    return Detail::get_calendar_available_formats(locale, calendar);
+#else
+    return {};
+#endif
+}
+
 }

Userland/Libraries/LibUnicode/DateTimeFormat.h

@@ -10,6 +10,7 @@
 #include <AK/String.h>
 #include <AK/StringView.h>
 #include <AK/Types.h>
+#include <AK/Vector.h>
 #include <LibUnicode/Forward.h>
 
 namespace Unicode {
@@ -56,5 +57,6 @@ struct CalendarFormat {
 CalendarPatternStyle calendar_pattern_style_from_string(StringView style);
 StringView calendar_pattern_style_to_string(CalendarPatternStyle style);
 Optional<CalendarFormat> get_calendar_format(StringView locale, StringView calendar, CalendarFormatType type);
+Vector<CalendarPattern> get_calendar_available_formats(StringView locale, StringView calendar);
 
 }