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

Configuration Object: Provides a configuration object that is easy to pass around for various different needs.
- The tab size and whether to expand them to spaces or not.
- The size of control characters.
- Whether to use alternate width calculation more suited for CJK contexts or not. It controls East Asian Ambiguous characters (such as Greek, Cyrillic, and some symbol characters) to be 1 or 2 columns wide.
- Also support the UNICODE_WIDTH=cjk environment variable to initialize the default CJK mode. This enables end users in CJK contexts to change the default mode to match their environments.
Safe Truncation: Truncate strings to a specific column width without breaking UTF-8 characters, including optional tab support.
Line Wrapping: Wrap strings to multiple lines at a specific column.

Installation

cargo add unicode-width-utils

Usage

Basic Example

use unicode_width_utils::UnicodeWidth;

fn main() {
    let uw = UnicodeWidth::new();
    assert_eq!(uw.char('A'), 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 mut uw = UnicodeWidth::with_cjk(false);
    assert_eq!(uw.char('█'), 1);

    // Treat ambiguous characters as 2 columns wide (CJK mode).
    uw.set_cjk(true);
    assert_eq!(cjk.char('█'), 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('█'), 2);
}

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

UNICODE_WIDTH=cjk

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 mut uw = UnicodeWidth::new();
    assert_eq!(uw.truncate("hello", 3), "hel");
    // 'あ' is 2 columns wide.
    assert_eq!(uw.truncate("あああ", 3), "あ");

    uw.set_tab_size(4);
    assert_eq!(uw.truncate("A\tB", 4), Cow::Owned::<str>("A\t".into()));
    uw.set_expand_tab(true);
    assert_eq!(uw.truncate("A\tB", 4), Cow::Owned::<str>("A   ".into()));
}

Line Wrapping

use unicode_width_utils::UnicodeWidth;

fn main() {
    let uw = UnicodeWidth::new();
    let lines: Vec<_> = uw.lines("12345678", 3).collect();
    assert_eq!(lines, vec!["123", "456", "78"]);
}

Please see the documentation for more details, and releases for the change history.

License

Licensed under the Apache License, Version 2.0.

unicode-width-utils 0.2.2