A readline replacement written in Rust

Introduction

Reedline is a project to create a readline-style crate for Rust that supports many of the modern conveniences of CLIs, including syntax highlighting, completions, multiline support, Unicode support, and more.

Examples

Basic example

// Create a default reedline object to handle user input

use reedline::{DefaultPrompt, Reedline, Signal};

fn main() {
    let mut line_editor = Reedline::create()?;
    let prompt = DefaultPrompt::default();

    loop {
        let sig = line_editor.read_line(&prompt).unwrap();
        match sig {
            Signal::Success(buffer) => {
                println!("We processed: {}", buffer);
            }
            Signal::CtrlD | Signal::CtrlC => {
                line_editor.print_crlf().unwrap();
                break;
            }
            Signal::CtrlL => {
                line_editor.clear_screen().unwrap();
            }
        }
    }
}

Integrate with custom Keybindings

// Configure reedline with custom keybindings

//Cargo.toml
//	[dependencies]
//	crossterm = "*"

use {
  crossterm::event::{KeyCode, KeyModifiers},
  reedline::{default_emacs_keybindings, EditCommand, Reedline},
};

let mut keybindings = default_emacs_keybindings();
keybindings.add_binding(
	KeyModifiers::ALT,
  KeyCode::Char('m'),
  vec![EditCommand::BackspaceWord],
);

let mut line_editor = Reedline::create()?.with_keybindings(keybindings);

Integrate with custom History

// Create a reedline object with history support, including history size limits

use reedline::{FileBackedHistory, Reedline};

let history = Box::new(
  FileBackedHistory::with_file(5, "history.txt".into())
  	.expect("Error configuring history with file"),
);
let mut line_editor = Reedline::create()?
	.with_history(history)
	.expect("Error configuring reedline with history");

Integrate with custom Highlighter

// Create a reedline object with highlighter support

use reedline::{DefaultHighlighter, Reedline};

let commands = vec![
  "test".into(),
  "hello world".into(),
  "hello world reedline".into(),
  "this is the reedline crate".into(),
];
let mut line_editor =
Reedline::create()?.with_highlighter(Box::new(DefaultHighlighter::new(commands)));

Integrate with custom Tab-Handler

// Create a reedline object with tab completions support

use reedline::{DefaultCompleter, CircularCompletionHandler, Reedline};

let commands = vec![
  "test".into(),
  "hello world".into(),
  "hello world reedline".into(),
  "this is the reedline crate".into(),
];
let completer = Box::new(DefaultCompleter::new_with_wordlen(commands.clone(), 2));

let mut line_editor = Reedline::create()?.with_completion_action_handler(Box::new(
  CircularCompletionHandler::default().with_completer(completer),
));

Integrate with custom Hinter

// Create a reedline object with in-line hint support

//Cargo.toml
//	[dependencies]
//	nu-ansi-term = "*"

use {
  nu_ansi_term::{Color, Style},
  reedline::{DefaultCompleter, DefaultHinter, Reedline},
};

let commands = vec![
  "test".into(),
  "hello world".into(),
  "hello world reedline".into(),
  "this is the reedline crate".into(),
];
let completer = Box::new(DefaultCompleter::new_with_wordlen(commands.clone(), 2));

let mut line_editor = Reedline::create()?.with_hinter(Box::new(
  DefaultHinter::default()
  .with_completer(completer) // or .with_history()
  // .with_inside_line()
  .with_style(Style::new().italic().fg(Color::LightGray)),
));

Integrate with custom line completion Validator

// Create a reedline object with line completion validation support

use reedline::{DefaultValidator, Reedline};

let validator = Box::new(DefaultValidator);

let mut line_editor = Reedline::create()?.with_validator(validator);

Integrate with custom Edit Mode

// Create a reedline object with custom edit mode

use reedline::{EditMode, Reedline};

let mut line_editor = Reedline::create()?.with_edit_mode(
  EditMode::ViNormal, // or EditMode::Emacs or EditMode::ViInsert
);

Are we prompt yet? (Development status)

This crate is currently under active development in JT's live-coding streams. If you want to see a feature, jump by the streams, file an issue or contribute a PR!

Basic unicode grapheme aware cursor editing.
Configurable prompt
Basic EMACS-style editing shortcuts.
Configurable keybindings.
Basic system integration with clipboard or optional stored history file.
Content aware highlighting.
Autocompletion.
Undo support.
Multiline aware editing with line completion validation.

For a more detailed roadmap check out TODO.txt.

Join the vision discussion in the vision milestone list by contributing suggestions or voting.

Alternatives

For currently more mature Rust line editing check out:

rustyline

aslynatilla/reedline