Repline: The Prebaked Multiline Editor

Repline is an easy-to-use, fairly sensible multiline terminal editor meant specifically for REPL-ifying existing Rust projects. It aims to provide a simple API and fairly intuitive™ keybinds, which will probably work in some terminals.

Repline is a component of the Conlang project.

Integrating Repline into your project

The easiest, most intuitive way to integrate Repline into your project is with the prebaked interface. This interface provides user input to a passed-in FnMut lambda as a string each time the user presses the enter key at the end of the last line.

use repline::prebaked::{read_and, Response};

fn main() -> Result<(), Box<dyn Error>> {
    // read_and takes three arguments: an ANSI terminal `color` string,
    // a `begin` prompt, which is shown on the first line,
    // and an `again` prompt, which is shown on subsequent lines.
    //
    // It returns a Result<(), repline::error::Error> on I/O failure.
    // `read_and` captures the Ctrl+C and Ctrl+D sequences.
    //
    // See its documentation for more info.
    read_and("", ".>", " >", |line| match line.trim() {
        // Returning Response::Continue will add a new line with the "again" prompt
        "" => Ok(Response::Continue),

        // Returning Response::Accept will add the input to history
        // and clear the input
        "accept" => Ok(Response::Accept),

        // Returning Response::Deny will just clear the input
        "deny" => Ok(Response::Deny),

        // Returning Response::Break will end the loop
        "exit" => Ok(Response::Break),

        // Returning an Err value will add a new line, (like Response::Continue,)
        // but show the formatted error value after the cursor.
        command => Err(format!("Unrecognized command: {command}"))?,
    })?;

    Ok(())
}

Advanced Repline integration

More complicated projects may have more complicated needs. To service these, the repline interface is exposed for direct consumption. This can be used if:

• You want to use a non-stdin source, such as a byte slice or file stream
  • See the error example.
• You want to switch input sources after startup
  • See the continue example.
• You want to customize the prompt in reaction to user input
  • Read the docs for repline::Repline