unicode-width-utils

A thin-wrapper for the unicode-width crate with additional functionalities, such as dynamic configuration for CJK (East Asian Ambiguous) widths and safe string truncation.

Features

Dynamic CJK Config: Treat East Asian Ambiguous characters (such as Greek, Cyrillic, and CJK characters) as either 1 or 2 columns wide.
Environment Variable Override: Initialize the default CJK mode using UNICODE_WIDTH=cjk.
Thread-safe Global Default: Change the global CJK default at runtime.
Safe Truncation: Truncate strings to a specific column width without breaking UTF-8 characters.

Installation

cargo add unicode-width-utils

Usage

Basic Example

use unicode_width_utils::UnicodeWidth;

fn main() {
    let uw = UnicodeWidth::new();
    
    // Non-CJK characters
    assert_eq!(uw.char('A'), Some(1));
    assert_eq!(uw.str("Hello"), 5);
}

CJK Ambiguous Widths

You can explicitly configure whether East Asian Ambiguous characters are treated as 1 or 2 columns wide:

use unicode_width_utils::UnicodeWidth;

fn main() {
    // Treat ambiguous characters as 1 column wide
    let non_cjk = UnicodeWidth::with_cjk(false);
    assert_eq!(non_cjk.char('█'), Some(1));

    // Treat ambiguous characters as 2 columns wide (CJK mode)
    let cjk = UnicodeWidth::with_cjk(true);
    assert_eq!(cjk.char('█'), Some(2));
}

Global Default Configuration

You can change the default configuration for future instances created via UnicodeWidth::new():

use unicode_width_utils::UnicodeWidth;

fn main() {
    // Globally set the default mode to CJK
    UnicodeWidth::set_default_cjk(true);
    
    let uw = UnicodeWidth::new();
    assert_eq!(uw.char('█'), Some(2));
}

Alternatively, you can initialize the default CJK mode via the environment variable:

UNICODE_WIDTH=cjk cargo run

String Truncation

Truncate a string slice so that its total display width does not exceed a maximum limit:

use unicode_width_utils::UnicodeWidth;

fn main() {
    let uw = UnicodeWidth::with_cjk(false);
    assert_eq!(uw.truncate("hello", 3), "hel");

    let cjk = UnicodeWidth::with_cjk(true);
    // 'あ' is 2 columns wide
    assert_eq!(cjk.truncate("あああ", 3), "あ");
    assert_eq!(cjk.truncate("A█B", 2), "A");
}

License

Licensed under the Apache License, Version 2.0.

unicode-width-utils 0.1.2