use std::io::{self, BufRead, BufReader, Stdin, Stdout, Write};
use std::process::{Child, ChildStdin, ChildStdout};
pub struct Connection<Source: BufRead, Sink: Write> {
source: Source,
sink: Sink,
}
impl<Source: BufRead, Sink: Write> Connection<Source, Sink> {
pub fn new(source: Source, sink: Sink) -> Self {
Self { source, sink }
}
}
impl Connection<BufReader<ChildStdout>, ChildStdin> {
pub fn new_from_child(child: Child) -> Option<Self> {
let stdin = child.stdin?;
let stdout = child.stdout?;
Some(Self {
source: BufReader::new(stdout),
sink: stdin,
})
}
}
impl Connection<BufReader<Stdin>, Stdout> {
pub fn new_from_current_process() -> Self {
Self {
source: BufReader::new(io::stdin()),
sink: io::stdout(),
}
}
}
impl<Source: BufRead, Sink: Write> Connection<Source, Sink> {
pub fn recv_message<T: serde::de::DeserializeOwned>(&mut self) -> Result<T, MessageIoError> {
let mut buf = String::new();
self.source
.read_line(&mut buf)
.map_err(MessageIoError::Recv)?;
Ok(serde_json::from_str(&buf)?)
}
pub fn send_message<T: serde::Serialize>(&mut self, t: &T) -> Result<(), MessageIoError> {
let json = serde_json::to_vec(t)?;
self.sink.write_all(&json).map_err(MessageIoError::Send)?;
self.sink.write_all(b"\n").map_err(MessageIoError::Send)?;
Ok(())
}
}
#[derive(Debug, thiserror::Error)]
pub enum MessageIoError {
#[error("failed receiving message from source")]
Recv(io::Error),
#[error("failed sending message to sink")]
Send(io::Error),
#[error("failed deserializing JSON")]
Json(#[from] serde_json::Error),
}