LibLocale: Add a method to access a locale's digital format options

For Intl.DurationFormat, we will need to know a locale's hours-minutes
time separator, minutes-seconds time separator, and whether the locale
prefers digital hours to always display as 2 digits.

Userland/Libraries/LibLocale/CMakeLists.txt

@@ -11,6 +11,7 @@ endif()
 
 set(SOURCES
     DateTimeFormat.cpp
+    DurationFormat.cpp
     DisplayNames.cpp
     ICU.cpp
     ListFormat.cpp

Userland/Libraries/LibLocale/DurationFormat.cpp

@@ -0,0 +1,88 @@
+/*
+ * Copyright (c) 2024, Tim Flynn <trflynn89@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#define AK_DONT_REPLACE_STD
+
+#include <AK/Array.h>
+#include <AK/CharacterTypes.h>
+#include <AK/GenericLexer.h>
+#include <LibLocale/DurationFormat.h>
+#include <LibLocale/ICU.h>
+#include <LibLocale/NumberFormat.h>
+
+#include <unicode/measfmt.h>
+#include <unicode/measunit.h>
+#include <unicode/measure.h>
+
+namespace Locale {
+
+static constexpr bool is_not_ascii_digit(u32 code_point)
+{
+    return !is_ascii_digit(code_point);
+}
+
+DigitalFormat digital_format(StringView locale)
+{
+    UErrorCode status = U_ZERO_ERROR;
+
+    auto locale_data = LocaleData::for_locale(locale);
+    if (!locale_data.has_value())
+        return {};
+
+    if (auto const& digital_format = locale_data->digital_format(); digital_format.has_value())
+        return *digital_format;
+
+    RoundingOptions rounding_options;
+    rounding_options.type = RoundingType::SignificantDigits;
+    rounding_options.min_significant_digits = 1;
+    rounding_options.max_significant_digits = 2;
+
+    auto number_formatter = NumberFormat::create(locale, "latn"sv, {}, rounding_options);
+
+    auto icu_locale = adopt_own(*locale_data->locale().clone());
+    icu_locale->setUnicodeKeywordValue("nu", "latn", status);
+    if (icu_failure(status))
+        return {};
+
+    icu::MeasureFormat measurement_formatter(*icu_locale, UMEASFMT_WIDTH_NUMERIC, status);
+    if (icu_failure(status))
+        return {};
+
+    auto measures = to_array<icu::Measure>({
+        { 1, icu::MeasureUnit::createHour(status), status },
+        { 22, icu::MeasureUnit::createMinute(status), status },
+        { 33, icu::MeasureUnit::createSecond(status), status },
+    });
+    if (icu_failure(status))
+        return {};
+
+    icu::UnicodeString formatted;
+    icu::FieldPosition position;
+    measurement_formatter.formatMeasures(measures.data(), static_cast<i32>(measures.size()), formatted, position, status);
+    if (icu_failure(status))
+        return {};
+
+    auto hours_minutes_seconds = icu_string_to_string(formatted);
+    GenericLexer lexer { hours_minutes_seconds };
+
+    DigitalFormat digital_format;
+
+    auto hours = lexer.consume_while(is_ascii_digit);
+    digital_format.uses_two_digit_hours = hours.length() == 2;
+
+    auto hours_minutes_separator = lexer.consume_while(is_not_ascii_digit);
+    digital_format.hours_minutes_separator = MUST(String::from_utf8(hours_minutes_separator));
+
+    lexer.ignore_while(is_ascii_digit);
+
+    auto minutes_seconds_separator = lexer.consume_while(is_not_ascii_digit);
+    digital_format.minutes_seconds_separator = MUST(String::from_utf8(minutes_seconds_separator));
+
+    locale_data->set_digital_format(move(digital_format));
+    return *locale_data->digital_format();
+}
+
+}

Userland/Libraries/LibLocale/DurationFormat.h

@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2024, Tim Flynn <trflynn89@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/String.h>
+
+namespace Locale {
+
+struct DigitalFormat {
+    String hours_minutes_separator { ":"_string };
+    String minutes_seconds_separator { ":"_string };
+    bool uses_two_digit_hours { false };
+};
+
+DigitalFormat digital_format(StringView locale);
+
+}

Userland/Libraries/LibLocale/ICU.h

@@ -12,6 +12,7 @@
 #include <AK/OwnPtr.h>
 #include <AK/String.h>
 #include <AK/StringView.h>
+#include <LibLocale/DurationFormat.h>
 
 #include <unicode/locid.h>
 #include <unicode/stringpiece.h>
@@ -42,6 +43,9 @@ public:
 
     icu::TimeZoneNames& time_zone_names();
 
+    Optional<DigitalFormat> const& digital_format() { return m_digital_format; }
+    void set_digital_format(DigitalFormat digital_format) { m_digital_format = move(digital_format); }
+
 private:
     explicit LocaleData(icu::Locale locale);
 
@@ -52,6 +56,8 @@ private:
     OwnPtr<icu::LocaleDisplayNames> m_dialect_display_names;
     OwnPtr<icu::DateTimePatternGenerator> m_date_time_pattern_generator;
     OwnPtr<icu::TimeZoneNames> m_time_zone_names;
+
+    Optional<DigitalFormat> m_digital_format;
 };
 
 static constexpr bool icu_success(UErrorCode code)