Merge pull request #243 from mgeisler/release-0.13.0

Prepare changelog for version 0.13.0
tree: f0af2749071712b079d5dfd641a3fcc5433d80b9
  1. .github/
  2. .gitignore
  3. CHANGELOG.md
  4. Cargo.toml
  5. LICENSE
  6. README.md
  7. benches/
  8. examples/
  9. src/
  10. tests/
README.md

Textwrap

Textwrap is a library for word wrapping text. You can use it to format strings for display in commandline applications. The crate name and interface is inspired by the Python textwrap module.

Usage

To use textwrap, add this to your Cargo.toml file:

[dependencies]
textwrap = "0.13"

This gives you the text wrapping without of the optional Cargo features listed next.

hyphenation

If you would like to have automatic language-sensitive hyphenation, enable the hyphenation feature:

[dependencies]
textwrap = { version = "0.13", features = ["hyphenation"] }

This gives you hyphenation support for US English. Please see the hyphenation example for an executable demo. Read the Getting Started section below to see how to load the hyphenation patterns for other languages.

terminal_size

To conveniently wrap text at the current terminal width, enable the terminal_size feature:

[dependencies]
textwrap = { version = "0.13", features = ["terminal_size"] }

Please see the termwidth example for how to use this feature.

Documentation

API documentation

Getting Started

Word wrapping is easy using the fill function:

fn main() {
    let text = "textwrap: an efficient and powerful library for wrapping text.";
    println!("{}", textwrap::fill(text, 28));
}

The output is wrapped within 28 columns:

textwrap: an efficient
and powerful library for
wrapping text.

Sharp-eyed readers will notice that the first line is 22 columns wide. So why is the word “and” put in the second line when there is space for it in the first line?

The explanation is that textwrap does not just wrap text one line at a time. Instead, it uses an optimal-fit algorithm which looks ahead and chooses line breaks which minimize the gaps left at ends of lines.

Without look ahead, the first line would be longer and the text would look like this:

textwrap: an efficient and
powerful library for
wrapping text.

The second line is now shorter and the text is more ragged. The kind of wrapping can be configured via Option::wrap_algorithm.

If you enable the hyphenation Cargo feature, you get support for automatic hyphenation for about 70 languages via high-quality TeX hyphenation patterns.

Your program must load the hyphenation pattern and configure Options::splitter to use it:

use hyphenation::{Language, Load, Standard};
use textwrap::Options;

fn main() {
    let hyphenator = Standard::from_embedded(Language::EnglishUS).unwrap();
    let options = Options::new(28).splitter(hyphenator);
    let text = "textwrap: an efficient and powerful library for wrapping text.";
    println!("{}", fill(text, &options);
}

The output now looks like this:

textwrap: an efficient and
powerful library for wrap-
ping text.

The US-English hyphenation patterns are embedded when you enable the hyphenation feature. They are licensed under a permissive license and take up about 88 KB in your binary. If you need hyphenation for other languages, you need to download a precompiled .bincode file and load it yourself. Please see the hyphenation documentation for details.

Wrapping Strings at Compile Time

If your strings are known at compile time, please take a look at the procedural macros from the textwrap-macros crate.

Examples

The library comes with a collection of small example programs that shows various features. You’re invited to clone the repository and try them out for yourself!

Of special note is the interactive example. This is a demo program which demonstrates most of the available features: you can enter text and adjust the width at which it is wrapped interactively. You can also adjust the Options used to see the effect of different WordSplitters and wrap algorithms.

Run the demo with

$ cargo run --example interactive

The demo needs a Linux terminal to function.

Release History

Please see the CHANGELOG file for details on the changes made in each release.

License

Textwrap can be distributed according to the MIT license. Contributions will be accepted under the same license.