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#![forbid(unsafe_code)]
#![warn(missing_docs, clippy::missing_docs_in_private_items)]
use std::{
convert::TryInto,
io::{Read, Write},
};
use byteorder::{NativeEndian, ReadBytesExt, WriteBytesExt};
#[derive(Debug, thiserror::Error)]
pub enum MessagingError {
#[error(transparent)]
Infallible(#[from] std::convert::Infallible),
#[error(transparent)]
Io(#[from] std::io::Error),
#[error(transparent)]
Json(#[from] serde_json::Error),
#[error(transparent)]
TryFromInt(#[from] std::num::TryFromIntError),
}
pub(crate) fn generic_read_message<D, R>(
mut reader: R,
) -> Result<D, MessagingError>
where
D: for<'a> serde::Deserialize<'a>,
R: Read,
{
let message_length = reader.read_u32::<NativeEndian>()?.try_into()?;
let message_bytes = reader.take(message_length);
serde_json::from_reader(message_bytes).map_err(Into::into)
}
pub fn read_message<D>() -> Result<D, MessagingError>
where
D: for<'a> serde::Deserialize<'a>,
{
let stdin = std::io::stdin();
let stdin = stdin.lock();
generic_read_message(stdin)
}
pub(crate) fn generic_write_message<S, W>(
message: &S,
mut writer: W,
) -> Result<(), MessagingError>
where
S: serde::Serialize,
W: Write,
{
let message_bytes = serde_json::to_vec(message)?;
let message_length = message_bytes.len().try_into()?;
writer.write_u32::<NativeEndian>(message_length)?;
writer.write_all(&message_bytes)?;
writer.flush().map_err(MessagingError::Io)
}
pub fn write_message<S>(message: &S) -> Result<(), MessagingError>
where
S: serde::Serialize,
{
let stdout = std::io::stdout();
let stdout = stdout.lock();
generic_write_message(message, stdout)
}
#[cfg(test)]
pub(crate) mod tests {
use crate::{generic_read_message, generic_write_message, MessagingError};
#[derive(Debug, serde::Deserialize, serde::Serialize, PartialEq)]
struct Message {
text: String,
}
#[test]
fn test_messaging() -> Result<(), MessagingError> {
let test_message = Message {
text: "This is a test".to_string(),
};
let mut buffer: Vec<u8> = vec![];
generic_write_message(&test_message, &mut buffer)?;
let message = generic_read_message::<Message, _>(&*buffer)?;
assert_eq!(message, test_message);
Ok(())
}
}