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use futures::future::{Future as _, IntoFuture as _};
use futures::stream::Stream as _;
use snafu::ResultExt as _;
use std::io::Write as _;
#[derive(Debug, snafu::Snafu)]
pub enum Error {
#[snafu(display("error during read: {}", source))]
Read { source: crate::readline::Error },
#[snafu(display("error during eval: {}", source))]
Eval { source: crate::eval::Error },
#[snafu(display("error during print: {}", source))]
Print { source: std::io::Error },
}
pub type Result<T> = std::result::Result<T, Error>;
pub fn repl() {
let loop_stream = futures::stream::unfold(false, |done| {
if done {
return None;
}
let repl = read().and_then(|line| {
eprint!("running '{}'\r\n", line);
eval(&line).fold(None, |acc, event| match event {
crate::eval::CommandEvent::Output(out) => match print(&out) {
Ok(()) => futures::future::ok(acc),
Err(e) => futures::future::err(e),
},
crate::eval::CommandEvent::ProcessExit(status) => {
futures::future::ok(Some(format!("{}", status)))
}
crate::eval::CommandEvent::BuiltinExit => {
futures::future::ok(Some("success".to_string()))
}
})
});
Some(repl.then(move |res| match res {
Ok(Some(status)) => {
eprint!("command exited: {}\r\n", status);
Ok((done, false))
}
Ok(None) => {
eprint!("command exited weirdly?\r\n");
Ok((done, false))
}
Err(Error::Read {
source: crate::readline::Error::EOF,
}) => Ok((done, true)),
Err(Error::Eval {
source:
crate::eval::Error::Parser {
source: crate::parser::Error::CommandRequired,
..
},
}) => Ok((done, false)),
Err(e) => {
let stderr = std::io::stderr();
let mut stderr = stderr.lock();
// panics seem fine for errors during error handling
write!(stderr, "{}\r\n", e).unwrap();
stderr.flush().unwrap();
Ok((done, false))
}
}))
});
tokio::run(loop_stream.collect().map(|_| ()));
}
fn read() -> impl futures::future::Future<Item = String, Error = Error> {
crate::readline::readline("$ ", true)
.into_future()
.flatten()
.map_err(|e| Error::Read { source: e })
}
fn eval(
line: &str,
) -> impl futures::stream::Stream<Item = crate::eval::CommandEvent, Error = Error>
{
crate::eval::eval(line)
.into_future()
.flatten_stream()
.map_err(|e| Error::Eval { source: e })
}
fn print(out: &[u8]) -> Result<()> {
let stdout = std::io::stdout();
let mut stdout = stdout.lock();
stdout.write(out).context(Print)?;
stdout.flush().context(Print)
}
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