ferrocat

ferrocat is the public Rust crate in the ferrocat workspace.

It provides:

PO parsing and serialization
ICU MessageFormat parsing and serializable compilation
Catalog compilation for serializable host bindings
Message ID generation and plural helpers
A Rust-only runtime module for locale-aware formatting and tag rendering

The crate is intended to be usable directly from Rust and to serve as the shared core for thin host bindings such as Node.js.

Installation

cargo add ferrocat

Parse and stringify PO files

use ferrocat::{parse_po, stringify_po, SerializeOptions};

let po = parse_po(
    r#"
msgid ""
msgstr ""
"Language: de\n"

msgid "Hello"
msgstr "Hallo"
"#,
);

assert_eq!(po.items[0].msgid, "Hello");
assert_eq!(po.items[0].msgstr, vec!["Hallo"]);

let rendered = stringify_po(&po, SerializeOptions::default());
assert!(rendered.contains(r#"msgid "Hello""#));

Compile ICU messages to a serializable payload

use ferrocat::{compile_icu, CompileIcuOptions, SerializedCompiledMessageKind};

let compiled = compile_icu(
    "{count, plural, one {# file} other {# files}}",
    &CompileIcuOptions::new("en"),
)
.expect("message should compile");

match compiled.kind {
    SerializedCompiledMessageKind::Icu { ast } => assert!(!ast.is_empty()),
    other => panic!("expected icu payload, got {other:?}"),
}

Compile catalogs to a serializable payload

use ferrocat::{
    compile_catalog, Catalog, CatalogEntry, CatalogTranslation, CompileCatalogOptions,
    SerializedCompiledMessageKind,
};

let catalog = Catalog::from([(
    "Hello {name}!".to_owned(),
    CatalogEntry {
        translation: Some(CatalogTranslation::Singular("Hallo {name}!".to_owned())),
        ..CatalogEntry::default()
    },
)]);

let compiled = compile_catalog(&catalog, &CompileCatalogOptions::new("de"))
    .expect("catalog should compile");
assert_eq!(compiled.entries.len(), 1);
match &compiled.entries[0].message.kind {
    SerializedCompiledMessageKind::Icu { ast } => assert!(!ast.is_empty()),
    other => panic!("expected icu payload, got {other:?}"),
}

Rust runtime formatting

For direct runtime formatting in Rust, use [ferrocat::runtime]. It exposes the runtime compiler, compiled message/catalog types, and host hooks such as FormatHost.