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use snafu::{ResultExt, Snafu};
#[derive(Debug, Snafu)]
pub enum Error {
#[snafu(display("unknown builtin {}", cmd))]
UnknownBuiltin { cmd: String },
#[snafu(display("failed to cd to {}: {}", dir, source))]
Chdir { dir: String, source: nix::Error },
#[snafu(display("cd requires a directory to be given"))]
ChdirParams,
}
pub fn exec(cmd: &str, args: &[String]) -> Result<Builtin, Error> {
Builtin::new(cmd, args)
}
pub struct Builtin {
cmd: String,
args: Vec<String>,
done: bool,
}
impl Builtin {
fn new(cmd: &str, args: &[String]) -> Result<Self, Error> {
match cmd {
"cd" => Ok(Builtin {
cmd: cmd.to_string(),
args: args.to_vec(),
done: false,
}),
_ => Err(Error::UnknownBuiltin {
cmd: cmd.to_string(),
}),
}
}
}
#[must_use = "streams do nothing unless polled"]
impl futures::stream::Stream for Builtin {
type Item = crate::eval::CommandEvent;
type Error = Error;
fn poll(&mut self) -> futures::Poll<Option<Self::Item>, Self::Error> {
if self.done {
return Ok(futures::Async::Ready(None));
}
self.done = true;
let res = match self.cmd.as_ref() {
"cd" => cd(&self.args),
_ => Err(Error::UnknownBuiltin {
cmd: self.cmd.clone(),
}),
};
res.map(|_| {
futures::Async::Ready(Some(
crate::eval::CommandEvent::BuiltinExit,
))
})
}
}
fn cd(args: &[String]) -> Result<(), Error> {
if let Some(dir) = args.get(0) {
nix::unistd::chdir(dir.as_str()).context(Chdir { dir: dir.clone() })
} else {
Err(Error::ChdirParams)
}
}
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