# clap-repl
[](https://github.com/HKalbasi/clap-repl/actions/workflows/rust.yml)
[](https://crates.io/crates/clap-repl)
One of the typical user interfaces for prompting commands is the repl (read eval print loop). One of the best ways of representing commands in a repl
is using space separated arguments, which is what terminal shells do. And the way to parse such commands in Rust is the `clap` crate. This crate uses
`clap` and `rustyline` to provide such user interface in a way that you only focus on your app logic.
## Features
Thanks to `clap` and `rustyline` this crate handles:
* Parsing the space separated commands into your data structure.
* Help flag for each command.
* Verifying the command is valid, generating useful errors and suggestions otherwise.
* Auto complete and hint for the commands.
## Example
```Rust
use clap::Parser;
use clap_repl::ClapEditor;
use console::style;
use rustyline::DefaultEditor;
#[derive(Debug, Parser)]
#[command(name = "")] // This name will show up in clap's error messages, so it is important to set it to "".
enum SampleCommand {
Download {
path: String,
/// Some explanation about what this flag do.
#[arg(long)]
check_sha: bool,
},
/// A command to upload things.
Upload,
Login {
/// Optional. You will be prompted if you don't provide it.
#[arg(short, long)]
username: Option<String>,
},
}
fn main() {
// Use `ClapEditor` instead of the `rustyline::DefaultEditor`.
let mut rl = ClapEditor::<SampleCommand>::new();
loop {
// Use `read_command` instead of `readline`.
let Some(command) = rl.read_command() else {
continue;
};
match command {
SampleCommand::Download { path, check_sha } => {
println!("Downloaded {path} with checking = {check_sha}");
},
SampleCommand::Upload => {
println!("Uploaded");
},
SampleCommand::Login { username } => {
// You can use another `rustyline::Editor` inside the loop.
let mut rl = DefaultEditor::new().unwrap();
let username = username.unwrap_or_else(|| rl.readline(&style("What is your username? ").bold().to_string()).unwrap());
let password = rl.readline(&style("What is your password? ").bold().to_string()).unwrap();
println!("Logged in with {username} and {password}");
},
}
}
}
```
