use crate::stream::{Fuse, IntoStream, StreamExt};
use alloc::vec::Vec;
use core::fmt;
use core::pin::Pin;
use futures_core::stream::{FusedStream, Stream, TryStream};
use futures_core::task::{Context, Poll};
#[cfg(feature = "sink")]
use futures_sink::Sink;
use pin_project_lite::pin_project;
pin_project! {
#[derive(Debug)]
#[must_use = "streams do nothing unless polled"]
pub struct TryReadyChunks<St: TryStream> {
#[pin]
stream: Fuse<IntoStream<St>>,
cap: usize, }
}
impl<St: TryStream> TryReadyChunks<St> {
pub(super) fn new(stream: St, capacity: usize) -> Self {
assert!(capacity > 0);
Self { stream: IntoStream::new(stream).fuse(), cap: capacity }
}
delegate_access_inner!(stream, St, (. .));
}
type TryReadyChunksStreamError<St> =
TryReadyChunksError<<St as TryStream>::Ok, <St as TryStream>::Error>;
impl<St: TryStream> Stream for TryReadyChunks<St> {
type Item = Result<Vec<St::Ok>, TryReadyChunksStreamError<St>>;
fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
let mut this = self.as_mut().project();
let mut items: Vec<St::Ok> = Vec::new();
loop {
match this.stream.as_mut().poll_next(cx) {
Poll::Pending => {
return if items.is_empty() {
Poll::Pending
} else {
Poll::Ready(Some(Ok(items)))
}
}
Poll::Ready(Some(Ok(item))) => {
if items.is_empty() {
items.reserve_exact(*this.cap);
}
items.push(item);
if items.len() >= *this.cap {
return Poll::Ready(Some(Ok(items)));
}
}
Poll::Ready(Some(Err(e))) => {
return Poll::Ready(Some(Err(TryReadyChunksError(items, e))));
}
Poll::Ready(None) => {
let last = if items.is_empty() { None } else { Some(Ok(items)) };
return Poll::Ready(last);
}
}
}
}
fn size_hint(&self) -> (usize, Option<usize>) {
let (lower, upper) = self.stream.size_hint();
let lower = lower / self.cap;
(lower, upper)
}
}
impl<St: TryStream + FusedStream> FusedStream for TryReadyChunks<St> {
fn is_terminated(&self) -> bool {
self.stream.is_terminated()
}
}
#[cfg(feature = "sink")]
impl<S, Item> Sink<Item> for TryReadyChunks<S>
where
S: TryStream + Sink<Item>,
{
type Error = <S as Sink<Item>>::Error;
delegate_sink!(stream, Item);
}
#[derive(PartialEq, Eq)]
pub struct TryReadyChunksError<T, E>(pub Vec<T>, pub E);
impl<T, E: fmt::Debug> fmt::Debug for TryReadyChunksError<T, E> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.1.fmt(f)
}
}
impl<T, E: fmt::Display> fmt::Display for TryReadyChunksError<T, E> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.1.fmt(f)
}
}
#[cfg(feature = "std")]
impl<T, E: fmt::Debug + fmt::Display> std::error::Error for TryReadyChunksError<T, E> {}