multipart_write/write/
extend.rs

1use crate::MultipartWrite;
2
3use std::fmt::{self, Debug, Formatter};
4use std::io::Error as IoError;
5use std::marker::PhantomData;
6use std::pin::Pin;
7use std::task::{Context, Poll};
8
9/// Converts an `Extend` into a `MultipartWrite` that is always ready to receive
10/// the next part to write.
11pub fn extend<T, A>(inner: T) -> Extend<T, A>
12where
13    T: std::iter::Extend<A>,
14{
15    Extend::new(inner)
16}
17
18pin_project_lite::pin_project! {
19    /// `MultipartWrite` for the [`extend`] function.
20    #[must_use = "futures do nothing unless polled"]
21    pub struct Extend<T, A> {
22        inner: Option<T>,
23        _a: PhantomData<A>,
24    }
25}
26
27impl<T, A> Extend<T, A> {
28    fn new(inner: T) -> Self {
29        Extend {
30            inner: Some(inner),
31            _a: PhantomData,
32        }
33    }
34}
35
36impl<T, A> MultipartWrite<A> for Extend<T, A>
37where
38    T: std::iter::Extend<A>,
39{
40    type Error = IoError;
41    type Ret = ();
42    type Output = T;
43
44    fn poll_ready(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
45        Poll::Ready(Ok(()))
46    }
47
48    fn start_send(mut self: Pin<&mut Self>, part: A) -> Result<Self::Ret, Self::Error> {
49        let Some(ext) = self.inner.as_mut() else {
50            return Err(IoError::other("unset"));
51        };
52        ext.extend([part]);
53        Ok(())
54    }
55
56    fn poll_flush(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
57        Poll::Ready(Ok(()))
58    }
59
60    fn poll_complete(
61        mut self: Pin<&mut Self>,
62        _cx: &mut Context<'_>,
63    ) -> Poll<Result<Self::Output, Self::Error>> {
64        let out = self.inner.take();
65        if out.is_none() {
66            return Poll::Ready(Err(IoError::other("unset")));
67        }
68        Poll::Ready(Ok(out.unwrap()))
69    }
70}
71
72impl<T, A> Debug for Extend<T, A>
73where
74    T: Debug,
75{
76    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
77        f.debug_struct("Extend")
78            .field("inner", &self.inner)
79            .finish()
80    }
81}
multipart_write/write/extend.rs

multipart_write/write/
extend.rs
