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use std::error::Error;
use std::fmt::Debug;
use std::pin::Pin;
use std::task::{Context, Poll};
use bytes::Buf;
use http_body::{Body, Frame, SizeHint};
use proj::EitherProj;
#[derive(Debug, Clone, Copy)]
pub enum Either<L, R> {
Left(L),
Right(R),
}
impl<L, R> Either<L, R> {
pub(crate) fn project(self: Pin<&mut Self>) -> EitherProj<L, R> {
unsafe {
match self.get_unchecked_mut() {
Self::Left(left) => EitherProj::Left(Pin::new_unchecked(left)),
Self::Right(right) => EitherProj::Right(Pin::new_unchecked(right)),
}
}
}
}
impl<L> Either<L, L> {
pub fn into_inner(self) -> L {
match self {
Either::Left(left) => left,
Either::Right(right) => right,
}
}
}
impl<L, R, Data> Body for Either<L, R>
where
L: Body<Data = Data>,
R: Body<Data = Data>,
L::Error: Into<Box<dyn Error + Send + Sync>>,
R::Error: Into<Box<dyn Error + Send + Sync>>,
Data: Buf,
{
type Data = Data;
type Error = Box<dyn Error + Send + Sync>;
fn poll_frame(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
) -> Poll<Option<Result<Frame<Self::Data>, Self::Error>>> {
match self.project() {
EitherProj::Left(left) => left
.poll_frame(cx)
.map(|poll| poll.map(|opt| opt.map_err(Into::into))),
EitherProj::Right(right) => right
.poll_frame(cx)
.map(|poll| poll.map(|opt| opt.map_err(Into::into))),
}
}
fn is_end_stream(&self) -> bool {
match self {
Either::Left(left) => left.is_end_stream(),
Either::Right(right) => right.is_end_stream(),
}
}
fn size_hint(&self) -> SizeHint {
match self {
Either::Left(left) => left.size_hint(),
Either::Right(right) => right.size_hint(),
}
}
}
pub(crate) mod proj {
use std::marker::PhantomData;
use std::pin::Pin;
use super::Either;
#[allow(dead_code)]
#[allow(single_use_lifetimes)]
#[allow(unknown_lints)]
#[allow(clippy::mut_mut)]
#[allow(clippy::redundant_pub_crate)]
#[allow(clippy::ref_option_ref)]
#[allow(clippy::type_repetition_in_bounds)]
pub(crate) enum EitherProj<'__pin, L, R>
where
Either<L, R>: '__pin,
{
Left(Pin<&'__pin mut L>),
Right(Pin<&'__pin mut R>),
}
#[allow(single_use_lifetimes)]
#[allow(unknown_lints)]
#[allow(clippy::used_underscore_binding)]
#[allow(missing_debug_implementations)]
const _: () = {
#[allow(non_snake_case)]
pub struct __Origin<'__pin, L, R> {
__dummy_lifetime: PhantomData<&'__pin ()>,
_Left: L,
_Right: R,
}
impl<'__pin, L, R> Unpin for Either<L, R> where __Origin<'__pin, L, R>: Unpin {}
trait MustNotImplDrop {}
#[allow(drop_bounds)]
impl<T: Drop> MustNotImplDrop for T {}
impl<L, R> MustNotImplDrop for Either<L, R> {}
};
}
#[cfg(test)]
mod tests {
use super::*;
use crate::{BodyExt, Empty, Full};
#[tokio::test]
async fn data_left() {
let full = Full::new(&b"hello"[..]);
let mut value: Either<_, Empty<&[u8]>> = Either::Left(full);
assert_eq!(value.size_hint().exact(), Some(b"hello".len() as u64));
assert_eq!(
value.frame().await.unwrap().unwrap().into_data().unwrap(),
&b"hello"[..]
);
assert!(value.frame().await.is_none());
}
#[tokio::test]
async fn data_right() {
let full = Full::new(&b"hello!"[..]);
let mut value: Either<Empty<&[u8]>, _> = Either::Right(full);
assert_eq!(value.size_hint().exact(), Some(b"hello!".len() as u64));
assert_eq!(
value.frame().await.unwrap().unwrap().into_data().unwrap(),
&b"hello!"[..]
);
assert!(value.frame().await.is_none());
}
#[test]
fn into_inner() {
let a = Either::<i32, i32>::Left(2);
assert_eq!(a.into_inner(), 2)
}
}