formatjs_icu_messageformat

Rust runtime for ICU MessageFormat. Mirrors intl-messageformat around the existing formatjs_icu_messageformat_parser AST and uses ICU4X for locale-aware number, date/time, and plural formatting.

use formatjs_icu_messageformat::{IcuMessageFormat, Value};
use std::collections::HashMap;

let message = IcuMessageFormat::try_new(
    "Hello, {name}. You have {count, plural, one {# task} other {# tasks}}.",
)?;
let values = HashMap::from([
    ("name".to_owned(), Value::from("Ada")),
    ("count".to_owned(), Value::from(2_i64)),
]);
assert_eq!(
    message.format_to_string("en-US", &values)?,
    "Hello, Ada. You have 2 tasks."
);
# Ok::<(), formatjs_icu_messageformat::Error>(())

Messages are parsed once without a locale. Pass each request's locale to format, format_to_parts, or format_to_string; one compiled message can be shared across requests with different locales.

Unix epoch millisecond values are formatted in UTC. ICU4X currently lacks full ECMA-402 currency, unit, and time-zone formatting parity; custom implementations can be supplied through the Formatters trait.