Shelgon

Shelgon is a robust Rust framework for building interactive REPL (Read-Eval-Print Loop) applications and custom shells. It provides a flexible, type-safe foundation with built-in terminal UI capabilities using ratatui.

Features

• 🛡️ Type-safe Command Execution - Like Shelgon's protective shell, your commands are wrapped in a type-safe interface
• 🔄 Async Runtime Integration - Built on tokio for high-performance async operations
• 🎨 Beautiful TUI - Powered by ratatui with support for styling and colors
• ⌨️ Rich Input Handling - Complete keyboard interaction support including:
  • Command history
  • Cursor movement
  • Tab completion
  • Ctrl+C/Ctrl+D handling
• 📝 Custom Context Support - Maintain state between commands with your own context type
• 📥 STDIN Support - Handle multi-line input for commands that need it

Installation

Add Shelgon to your Cargo.toml:

[dependencies]
shelgon = "0.1.0"
tokio = { version = "1.43.0", features = ["full"] }
anyhow = "1.0.95"

Quick Start

Create a simple echo shell:

use shelgon::{command, renderer};

struct EchoExecutor {}

impl command::New for EchoExecutor {
    fn new() -> anyhow::Result<(Self, ())> {
        Ok((Self {}, ()))
    }
}

impl command::Execute for EchoExecutor {
    type Context = ();

    fn prompt(&self, _: &Self::Context) -> String {
        "$".to_string()
    }

    fn execute(
        &self,
        _: &mut Self::Context,
        cmd: command::CommandInput,
    ) -> anyhow::Result<command::OutputAction> {
        Ok(command::OutputAction::Command(command::CommandOutput {
            prompt: cmd.prompt,
            command: cmd.command.clone(),
            stdin: cmd.stdin.unwrap_or_default(),
            stdout: vec![cmd.command],
            stderr: Vec::new(),
        }))
    }
}

fn main() -> anyhow::Result<()> {
    let rt = tokio::runtime::Runtime::new()?;
    let app = renderer::App::<EchoExecutor>::new(rt)?;
    app.execute()
}

Evolution Guide: Building Your Own Shell

Here's how to build a dragon-like shell with shelgon:

1. Define Your Executor: Create a type that implements command::Execute
2. Create Your Context: Design a context type to maintain state between commands
3. Implement Command Logic: Add your command execution logic in the execute method
4. Add Tab Completion: Implement the completion method for smart suggestions
5. Handle STDIN: Use the prepare method to indicate which commands need input

Examples

Check out the examples directory for more advanced usage patterns, including:

• echosh.rs: A basic echo shell demonstrating core functionality

Contributing

Contributions are welcome! Please feel free to submit a Pull Request. Before contributing, please:

1. Check existing issues or create a new one
2. Fork the repository
3. Create your feature branch (git checkout -b feature/amazing-feature)
4. Commit your changes (git commit -m 'Add some amazing feature')
5. Push to the branch (git push origin feature/amazing-feature)
6. Open a Pull Request

License

This project is licensed under the MIT License - see the LICENSE file for details.