tabwriter is a crate that implements elastic tabstops. It provides both a library for wrapping Rust Writers and a small program that exposes the same functionality at the command line.

Dual-licensed under MIT or the UNLICENSE.

use std::io::Write;
use tabwriter::TabWriter;
let mut tw = TabWriter::new(vec![]);
tw.write_all(b"
Bruce Springsteen\tBorn to Run
Bob Seger\tNight Moves
Metallica\tBlack
The Boss\tDarkness on the Edge of Town
").unwrap();
tw.flush().unwrap();
let written = String::from_utf8(tw.into_inner().unwrap()).unwrap();
assert_eq!(&written, "
Bruce Springsteen  Born to Run
Bob Seger          Night Moves
Metallica          Black
The Boss           Darkness on the Edge of Town
");

You can see an example of real use in my CSV toolkit.

[andrew@Liger tabwriter] cat sample | sed 's/   /\\t/g'
a\tb\tc
abc\tmnopqrstuv\txyz
abcmnoxyz\tmore text
a\tb\tc
[andrew@Liger tabwriter] ./target/tabwriter < sample
a          b           c
abc        mnopqrstuv  xyz
abcmnoxyz  more text
a   b   c

Notice that once a column block is broken, alignment starts over again.

The API is fully documented with some examples: https://burntsushi.net/rustdoc/tabwriter/.

This crate works with Cargo. Assuming you have Rust and Cargo installed, simply check out the source and run tests:

git clone git://github.com/BurntSushi/tabwriter
cd tabwriter
cargo test

You can also add tabwriter as a dependency to your project's Cargo.toml:

[dependencies]
tabwriter = "1"

If you want tabwriter to be aware of ANSI escape codes, then you should enable the TabWriter::ansi option. Previously this was done by enabling the crate feature ansi_formatting, but that feature is now deprecated. (If you use it, then TabWriter::ansi will be automatically enabled for you. Otherwise it is disabled by default.)

This crate's minimum supported rustc version is 1.67.0.

The current policy is that the minimum Rust version required to use this crate can be increased in minor version updates. For example, if crate 1.0 requires Rust 1.20.0, then crate 1.0.z for all values of z will also require Rust 1.20.0 or newer. However, crate 1.y for y > 0 may require a newer minimum version of Rust.

In general, this crate will be conservative with respect to the minimum supported version of Rust.