Textwrap

Textwrap is a small Rust crate 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

Add this to your Cargo.toml:

[dependencies]
textwrap = "0.4"

and this to your crate root:

extern crate textwrap;

If you would like to have automatic hyphenation, specify the dependency as:

[dependencies]
hyphenation = "0.6"
textwrap = { version: "0.4", features: ["hyphenation"] }

Documentation

API documentation

Getting Started

Word wrapping single strings is easy using the fill function:

extern crate textwrap;
use textwrap::fill;

fn main() {
    let text = "textwrap: a small library for wrapping text.";
    println!("{}", fill(text, 18));
}

The output is

textwrap: a small
library for
wrapping text.

With the hyphenation feature, you can get automatic hyphenation for about 70 languages. Your program must load and configure the hyphenation patterns to use:

extern crate hyphenation;
extern crate textwrap;

use hyphenation::Language;
use textwrap::Wrapper;

fn main() {
    let corpus = hyphenation::load(Language::English_US).unwrap();
    let mut wrapper = Wrapper::new(18);
    wrapper.corpus = Some(&corpus);
    let text = "textwrap: a small library for wrapping text.";
    println!("{}", wrapper.fill(text))
}

The output now looks like this:

textwrap: a small
library for wrap-
ping text.

The hyphenation uses high-quality TeX hyphenation patterns.

Examples

The library comes with a small example program that shows how a fixed example string is wrapped at different widths. Run the example with:

$ cargo run --features hyphenation --example layout

The program will use the following string:

Memory safety without garbage collection. Concurrency without data races. Zero-cost abstractions.

The string is wrapped at all widths between 15 and 60 columns. With narrow columns the output looks like this:

.--- Width: 15 ---.
| Memory safety   |
| without garbage |
| collection.     |
| Concurrency     |
| without data    |
| races. Zero-    |
| cost abstrac-   |
| tions.          |
.--- Width: 16 ----.
| Memory safety    |
| without garbage  |
| collection. Con- |
| currency without |
| data races. Ze-  |
| ro-cost abstrac- |
| tions.           |

Later, longer lines are used and the output now looks like this:

.-------------------- Width: 49 --------------------.
| Memory safety without garbage collection. Concur- |
| rency without data races. Zero-cost abstractions. |
.---------------------- Width: 53 ----------------------.
| Memory safety without garbage collection. Concurrency |
| without data races. Zero-cost abstractions.           |
.------------------------- Width: 59 -------------------------.
| Memory safety without garbage collection. Concurrency with- |
| out data races. Zero-cost abstractions.                     |

Notice how words are split at hyphens (such a s "zero-cost") but also how words are hyphenated using automatic/machine hyphenation.

Release History

This section lists the largest changes per release.

Version 0.4.0 — January 24th, 2017

Documented complexities and tested these via cargo bench.

• Fixed #13: Immediatedly add word if it fits
• Fixed #14: Avoid splitting on initial hyphens in --foo-bar

Version 0.3.0 — January 7th, 2017

Added support for automatic hyphenation.

Version 0.2.0 — December 28th, 2016

Introduced Wrapper struct. Added support for wrapping on hyphens.

Version 0.1.0 — December 17th, 2016

First public release with support for wrapping strings on whitespace.

License

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