Module enums

Enumerations over field sets.

These enumerations can be used when the field set is not known at compile time. However, they may contribute negatively to the binary size of the formatters.

The most general type is CompositeFieldSet, which supports all field sets in a single enumeration. CompositeDateTimeFieldSet is a good choice when you don’t need to format time zones.

Summary of all the types:

Type	Supported Field Sets
DateFieldSet	Date
CalendarPeriodFieldSet	Calendar Period
TimeFieldSet	Time
ZoneFieldSet	Zone
DateAndTimeFieldSet	Date + Time
CompositeDateTimeFieldSet	Date, Calendar Period, Time, Date + Time
CompositeFieldSet	All

Examples

Format with the time display depending on a runtime boolean:

use icu::calendar::Date;
use icu::datetime::fieldsets;
use icu::datetime::fieldsets::enums::CompositeDateTimeFieldSet;
use icu::datetime::input::{DateTime, Time};
use icu::datetime::DateTimeFormatter;
use icu::locale::locale;
use writeable::Writeable;

fn composite_field_set(
    should_display_time: bool,
) -> CompositeDateTimeFieldSet {
    if should_display_time {
        let field_set_with_options = fieldsets::MD::medium().with_time_hm();
        CompositeDateTimeFieldSet::DateTime(
            fieldsets::enums::DateAndTimeFieldSet::MDT(
                field_set_with_options,
            ),
        )
    } else {
        let field_set_with_options = fieldsets::MD::medium();
        CompositeDateTimeFieldSet::Date(fieldsets::enums::DateFieldSet::MD(
            field_set_with_options,
        ))
    }
}

let datetime = DateTime {
    date: Date::try_new_iso(2025, 1, 15).unwrap(),
    time: Time::try_new(16, 0, 0, 0).unwrap(),
};

let with_time = DateTimeFormatter::try_new(
    locale!("en-US").into(),
    composite_field_set(true),
)
.unwrap();
let without_time = DateTimeFormatter::try_new(
    locale!("en-US").into(),
    composite_field_set(false),
)
.unwrap();

assert_eq!(with_time.format(&datetime).to_string(), "Jan 15, 4:00 PM");
assert_eq!(without_time.format(&datetime).to_string(), "Jan 15");

Enums

CalendarPeriodFieldSet

An enumeration over all possible calendar period field sets.

CompositeDateTimeFieldSet

An enum supporting date, calendar period, time, and date+time field sets and options.

CompositeFieldSet

An enum supporting all possible field sets and options.

DateAndTimeFieldSet

An enumeration over all possible date+time composite field sets.

DateFieldSet

An enumeration over all possible date field sets.

TimeFieldSet

An enumeration over all possible time field sets.

ZoneFieldSet

An enumeration over all possible zone field sets.

Type Aliases

ZonedDateAndTimeFieldSet

Type alias representing all possible date + time + time zone field sets.

ZonedDateFieldSet

Type alias representing all possible date + time zone field sets.

ZonedTimeFieldSet

Type alias representing all possible time + time zone field sets.