LibJS: Implement Intl.RelativeTimeFormat.prototype.format

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

@@ -4,12 +4,13 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <AK/StringBuilder.h>
 #include <LibJS/Runtime/AbstractOperations.h>
 #include <LibJS/Runtime/GlobalObject.h>
-#include <LibJS/Runtime/Intl/AbstractOperations.h>
 #include <LibJS/Runtime/Intl/NumberFormat.h>
 #include <LibJS/Runtime/Intl/NumberFormatConstructor.h>
 #include <LibJS/Runtime/Intl/RelativeTimeFormat.h>
+#include <LibUnicode/NumberFormat.h>
 
 namespace JS::Intl {
 
@@ -122,4 +123,194 @@ ThrowCompletionOr<RelativeTimeFormat*> initialize_relative_time_format(GlobalObj
     return &relative_time_format;
 }
 
+// 17.1.2 SingularRelativeTimeUnit ( unit ), https://tc39.es/ecma402/#sec-singularrelativetimeunit
+ThrowCompletionOr<Unicode::TimeUnit> singular_relative_time_unit(GlobalObject& global_object, StringView unit)
+{
+    auto& vm = global_object.vm();
+
+    // 1. Assert: Type(unit) is String.
+
+    // 2. If unit is "seconds", return "second".
+    if (unit == "seconds"sv)
+        return Unicode::TimeUnit::Second;
+    // 3. If unit is "minutes", return "minute".
+    if (unit == "minutes"sv)
+        return Unicode::TimeUnit::Minute;
+    // 4. If unit is "hours", return "hour".
+    if (unit == "hours"sv)
+        return Unicode::TimeUnit::Hour;
+    // 5. If unit is "days", return "day".
+    if (unit == "days"sv)
+        return Unicode::TimeUnit::Day;
+    // 6. If unit is "weeks", return "week".
+    if (unit == "weeks"sv)
+        return Unicode::TimeUnit::Week;
+    // 7. If unit is "months", return "month".
+    if (unit == "months"sv)
+        return Unicode::TimeUnit::Month;
+    // 8. If unit is "quarters", return "quarter".
+    if (unit == "quarters"sv)
+        return Unicode::TimeUnit::Quarter;
+    // 9. If unit is "years", return "year".
+    if (unit == "years"sv)
+        return Unicode::TimeUnit::Year;
+
+    // 10. If unit is not one of "second", "minute", "hour", "day", "week", "month", "quarter", or "year", throw a RangeError exception.
+    // 11. Return unit.
+    if (auto time_unit = Unicode::time_unit_from_string(unit); time_unit.has_value())
+        return *time_unit;
+    return vm.throw_completion<RangeError>(global_object, ErrorType::IntlInvalidUnit, unit);
+}
+
+// 17.1.3 PartitionRelativeTimePattern ( relativeTimeFormat, value, unit ), https://tc39.es/ecma402/#sec-PartitionRelativeTimePattern
+ThrowCompletionOr<Vector<PatternPartitionWithUnit>> partition_relative_time_pattern(GlobalObject& global_object, RelativeTimeFormat& relative_time_format, double value, StringView unit)
+{
+    auto& vm = global_object.vm();
+
+    // 1. Assert: relativeTimeFormat has an [[InitializedRelativeTimeFormat]] internal slot.
+    // 2. Assert: Type(value) is Number.
+    // 3. Assert: Type(unit) is String.
+
+    // 4. If value is NaN, +∞𝔽, or -∞𝔽, throw a RangeError exception.
+    if (!Value(value).is_finite_number())
+        return vm.throw_completion<RangeError>(global_object, ErrorType::IntlNumberIsNaNOrInfinity);
+
+    // 5. Let unit be ? SingularRelativeTimeUnit(unit).
+    auto time_unit = TRY(singular_relative_time_unit(global_object, unit));
+
+    // 6. Let localeData be %RelativeTimeFormat%.[[LocaleData]].
+    // 7. Let dataLocale be relativeTimeFormat.[[DataLocale]].
+    auto const& data_locale = relative_time_format.data_locale();
+
+    // 8. Let fields be localeData.[[<dataLocale>]].
+
+    // 9. Let style be relativeTimeFormat.[[Style]].
+    auto style = relative_time_format.style();
+
+    // NOTE: The next steps form a "key" based on combining various formatting options into a string,
+    //       then filtering the large set of locale data down to the pattern we are looking for. Instead,
+    //       LibUnicode expects the individual options as enumeration values, and returns the couple of
+    //       patterns that match those options.
+    auto find_patterns_for_tense_or_number = [&](StringView tense_or_number) {
+        // 10. If style is equal to "short", then
+        //     a. Let entry be the string-concatenation of unit and "-short".
+        // 11. Else if style is equal to "narrow", then
+        //     a. Let entry be the string-concatenation of unit and "-narrow".
+        // 12. Else,
+        //     a. Let entry be unit.
+        auto patterns = Unicode::get_relative_time_format_patterns(data_locale, time_unit, tense_or_number, style);
+
+        // 13. If fields doesn't have a field [[<entry>]], then
+        if (patterns.is_empty()) {
+            // a. Let entry be unit.
+            // NOTE: In the CLDR, the lack of "short" or "narrow" in the key implies "long".
+            patterns = Unicode::get_relative_time_format_patterns(data_locale, time_unit, tense_or_number, Unicode::Style::Long);
+        }
+
+        // 14. Let patterns be fields.[[<entry>]].
+        return patterns;
+    };
+
+    // 15. Let numeric be relativeTimeFormat.[[Numeric]].
+    // 16. If numeric is equal to "auto", then
+    if (relative_time_format.numeric() == RelativeTimeFormat::Numeric::Auto) {
+        // a. Let valueString be ToString(value).
+        auto value_string = MUST(Value(value).to_string(global_object));
+
+        // b. If patterns has a field [[<valueString>]], then
+        if (auto patterns = find_patterns_for_tense_or_number(value_string); !patterns.is_empty()) {
+            VERIFY(patterns.size() == 1);
+
+            // i. Let result be patterns.[[<valueString>]].
+            auto result = patterns[0].pattern.to_string();
+
+            // ii. Return a List containing the Record { [[Type]]: "literal", [[Value]]: result }.
+            return Vector<PatternPartitionWithUnit> { { "literal"sv, move(result) } };
+        }
+    }
+
+    // 17. If value is -0𝔽 or if value is less than 0, then
+    StringView tense;
+    if (Value(value).is_negative_zero() || (value < 0)) {
+        // a. Let tl be "past".
+        tense = "past"sv;
+
+        // FIXME: The spec does not say to do this, but nothing makes sense after this with a negative value.
+        value = fabs(value);
+    }
+    // 18. Else,
+    else {
+        // a. Let tl be "future".
+        tense = "future"sv;
+    }
+
+    // 19. Let po be patterns.[[<tl>]].
+    auto patterns = find_patterns_for_tense_or_number(tense);
+
+    // 20. Let fv be ! PartitionNumberPattern(relativeTimeFormat.[[NumberFormat]], value).
+    auto value_partitions = partition_number_pattern(relative_time_format.number_format(), value);
+
+    // 21. Let pr be ! ResolvePlural(relativeTimeFormat.[[PluralRules]], value).
+    // 22. Let pattern be po.[[<pr>]].
+    // FIXME: Use ResolvePlural when Intl.PluralRules is implemented.
+    auto pattern = Unicode::select_pattern_with_plurality(patterns, value);
+    if (!pattern.has_value())
+        return Vector<PatternPartitionWithUnit> {};
+
+    // 23. Return ! MakePartsList(pattern, unit, fv).
+    return make_parts_list(pattern->pattern, Unicode::time_unit_to_string(time_unit), move(value_partitions));
+}
+
+// 17.1.4 MakePartsList ( pattern, unit, parts ), https://tc39.es/ecma402/#sec-makepartslist
+Vector<PatternPartitionWithUnit> make_parts_list(StringView pattern, StringView unit, Vector<PatternPartition> parts)
+{
+    // 1. Let patternParts be PartitionPattern(pattern).
+    auto pattern_parts = partition_pattern(pattern);
+
+    // 2. Let result be a new empty List.
+    Vector<PatternPartitionWithUnit> result;
+
+    // 3. For each Record { [[Type]], [[Value]] } patternPart in patternParts, do
+    for (auto& pattern_part : pattern_parts) {
+        // a. If patternPart.[[Type]] is "literal", then
+        if (pattern_part.type == "literal"sv) {
+            // i. Append Record { [[Type]]: "literal", [[Value]]: patternPart.[[Value]], [[Unit]]: empty } to result.
+            result.empend("literal"sv, move(pattern_part.value));
+        }
+        // b. Else,
+        else {
+            // i. Assert: patternPart.[[Type]] is "0".
+            VERIFY(pattern_part.type == "0"sv);
+
+            // ii. For each Record { [[Type]], [[Value]] } part in parts, do
+            for (auto& part : parts) {
+                // 1. Append Record { [[Type]]: part.[[Type]], [[Value]]: part.[[Value]], [[Unit]]: unit } to result.
+                result.empend(part.type, move(part.value), unit);
+            }
+        }
+    }
+
+    // 4. Return result.
+    return result;
+}
+
+// 17.1.5 FormatRelativeTime ( relativeTimeFormat, value, unit ), https://tc39.es/ecma402/#sec-FormatRelativeTime
+ThrowCompletionOr<String> format_relative_time(GlobalObject& global_object, RelativeTimeFormat& relative_time_format, double value, StringView unit)
+{
+    // 1. Let parts be ? PartitionRelativeTimePattern(relativeTimeFormat, value, unit).
+    auto parts = TRY(partition_relative_time_pattern(global_object, relative_time_format, value, unit));
+
+    // 2. Let result be an empty String.
+    StringBuilder result;
+
+    // 3. For each Record { [[Type]], [[Value]], [[Unit]] } part in parts, do
+    for (auto& part : parts) {
+        // a. Set result to the string-concatenation of result and part.[[Value]].
+        result.append(move(part.value));
+    }
+
+    // 4. Return result.
+    return result.build();
+}
+
 }