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use std::{fmt, io};

/// Interface for creating new commands
///
/// Defines io::Stdout as the default generic type.
/// Returning CommandResult::Break instructs the Cmd.run() loop to break.
///
/// # Examples
///
/// ```rust
/// // CommandHandler that prints out help message
/// use std::io;
/// use std::io::Write;
/// use rusty_cmd::command_handler::{CommandHandler, CommandResult};
///
/// #[derive(Debug, Default)]
/// pub struct Help;
///
/// impl CommandHandler for Help {
///     fn execute(&self, _stdout: &mut io::Stdout, _args: &[&str]) -> CommandResult {
///         writeln!(_stdout, "Help message").unwrap();
///         CommandResult::Continue
///     }
/// }
///
/// /// CommandHandler that prints out a greeting
/// #[derive(Debug, Default)]
/// pub struct Greet;
///
/// impl<W: io::Write> CommandHandler<W> for Greet {
///     fn execute(&self, _stdout: &mut W, _args: &[&str]) -> CommandResult {
///         let joined_args = _args.join(", ");
///         match _args.len() {
///             0 => _stdout.write(format!("Hello, {}!", joined_args).as_bytes()).unwrap(),
///             _ => _stdout.write(b"Hello!").unwrap(),
///         };
///         CommandResult::Continue
///     }
/// }
/// ```
pub trait CommandHandler<W = io::Stdout>: fmt::Debug {
    /// Required method to execute a command
    fn execute(&self, _stdout: &mut W, _args: &[&str]) -> CommandResult;
}

pub enum CommandResult {
    Continue,
    Break,
}