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use std::io::Write;
use clap::Command;
fn main() -> Result<(), String> {
loop {
let line = readline()?;
let line = line.trim();
if line.is_empty() {
continue;
}
match respond(line) {
Ok(quit) => {
if quit {
break;
}
}
Err(err) => {
write!(std::io::stdout(), "{err}").map_err(|e| e.to_string())?;
std::io::stdout().flush().map_err(|e| e.to_string())?;
}
}
}
Ok(())
}
fn respond(line: &str) -> Result<bool, String> {
let args = shlex::split(line).ok_or("error: Invalid quoting")?;
let matches = cli()
.try_get_matches_from(args)
.map_err(|e| e.to_string())?;
match matches.subcommand() {
Some(("ping", _matches)) => {
write!(std::io::stdout(), "Pong").map_err(|e| e.to_string())?;
std::io::stdout().flush().map_err(|e| e.to_string())?;
}
Some(("quit", _matches)) => {
write!(std::io::stdout(), "Exiting ...").map_err(|e| e.to_string())?;
std::io::stdout().flush().map_err(|e| e.to_string())?;
return Ok(true);
}
Some((name, _matches)) => unimplemented!("{name}"),
None => unreachable!("subcommand required"),
}
Ok(false)
}
fn cli() -> Command {
// strip out usage
const PARSER_TEMPLATE: &str = "\
{all-args}
";
// strip out name/version
const APPLET_TEMPLATE: &str = "\
{about-with-newline}\n\
{usage-heading}\n {usage}\n\
\n\
{all-args}{after-help}\
";
Command::new("repl")
.multicall(true)
.arg_required_else_help(true)
.subcommand_required(true)
.subcommand_value_name("APPLET")
.subcommand_help_heading("APPLETS")
.help_template(PARSER_TEMPLATE)
.subcommand(
Command::new("ping")
.about("Get a response")
.help_template(APPLET_TEMPLATE),
)
.subcommand(
Command::new("quit")
.alias("exit")
.about("Quit the REPL")
.help_template(APPLET_TEMPLATE),
)
}
fn readline() -> Result<String, String> {
write!(std::io::stdout(), "$ ").map_err(|e| e.to_string())?;
std::io::stdout().flush().map_err(|e| e.to_string())?;
let mut buffer = String::new();
std::io::stdin()
.read_line(&mut buffer)
.map_err(|e| e.to_string())?;
Ok(buffer)
}