localize_it - Simple and fast localization library

A tiny, zero-allocation localization system for Rust designed with #![no_std] support.

This crate provides a macro-based API for defining compile-time locales and localized string expressions without using dynamic memory, hash maps, or runtime lookups. All localized strings are stored in fixed-size arrays. You can manually control (via init_locale) the locale state or use the built-in locale storage (via init_locale_with_storage).

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Quick Example

With built-in locale storage:

use localize_it::{init_locale_with_storage, expressions, localize};

init_locale_with_storage!(EN, RU);

expressions!(
    HELLO => {
        EN: "Hello",
        RU: "Привет",
    },
    BYE => {
        EN: "Bye",
        RU: "Пока",
    },
);

fn main() {
    println!("{}", localize!(HELLO));
    println!("{}", localize!(BYE));
}

With manual control:

use localize_it::{init_locale, expression, localize};

init_locale!(EN, RU);

expression!(HELLO => {
    EN: "Hello",
    RU: "Привет",
});

fn main() {
    println!("{}", localize!(HELLO, Locale::EN));
}

---

Features

• O(1) localization lookup
• Zero allocations
• Macro-based API
• No external dependencies
• no_std compatible

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Design Constraints

• Not possible to update or add the translations without recompiling
• No plans to add automatic gender agreement, numeral declension, etc.

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Example With Recommended Project Structure

The recommended usage pattern is to create a dedicated locale module that contains locale initialization and grouped expression modules.

src/
├─ main.rs
└─ locale/
   ├─ mod.rs     # Locale initialization
   ├─ error.rs   # Expression module for error messages
   └─ ui.rs      # Expression module for UI elements

// mod.rs

pub mod error;
pub mod ui;

use localize_it::init_locale_with_storage;

// Initialize locale with two languages
init_locale_with_storage!(EN, RU);

// error.rs

use super::Expression;
use localize_it::expression;

// Create expression using the macro
expression!(ACTION_FAILED => {
    EN: "Action failed",
    RU: "Действие не выполнено",
});

// ui.rs

use super::Locale;
use localize_it::expression;

// Create another expression using the macro
expression!(BUTTON_TEXT => {
    EN: "Button text",
    RU: "Текст кнопки",
});

// main.rs (or wherever you want to use the localized strings)

use crate::locale::{error, get_locale, set_locale, ui, Locale};
use localize_it::localize;

fn main() {
    let current_locale = get_locale(); // Get current locale
    println!("{:?}", current_locale);

    set_locale(Locale::RU); // Set locale

    // Get one expression
    let error_message = localize!(error::ACTION_FAILED);
    println!("{}", error_message);

    // Get another expression
    let button_text = localize!(ui::BUTTON_TEXT);
    println!("{}", button_text);
}

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Usage

Add the following to your Cargo.toml:

[dependencies]
localize_it = "1.2.3"

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How It Works

• Locales are defined as an enum with #[repr(usize)]
• Expressions as an array of &'static str
• Built-in locale storage implemented as AtomicUsize with Relaxed ordering
• Localization resolves to a simple array index operation

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License

This project is licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE)

• MIT License (LICENSE-MIT)

at your option.