sinktools/
inspect.rs

1//! [`Inspect`] and related items.
2use core::pin::Pin;
3use core::task::{Context, Poll};
4
5use pin_project_lite::pin_project;
6
7use crate::{Sink, SinkBuild};
8
9pin_project! {
10    /// Same as [`core::iterator::Inspect`] but as a [`Sink`].
11    ///
12    /// Synchronously inspects items before sending them to the following sink.
13    #[must_use = "sinks do nothing unless polled"]
14    pub struct Inspect<Si, Func> {
15        #[pin]
16        sink: Si,
17        func: Func,
18    }
19}
20
21impl<Si, Func> Inspect<Si, Func> {
22    /// Creates with inspecting `func` and next `sink`.
23    pub fn new<Item>(func: Func, sink: Si) -> Self
24    where
25        Self: Sink<Item>,
26    {
27        Self { sink, func }
28    }
29}
30
31impl<Si, Func, Item> Sink<Item> for Inspect<Si, Func>
32where
33    Si: Sink<Item>,
34    Func: FnMut(&Item),
35{
36    type Error = Si::Error;
37
38    fn poll_ready(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
39        self.project().sink.poll_ready(cx)
40    }
41    fn start_send(self: Pin<&mut Self>, item: Item) -> Result<(), Self::Error> {
42        let this = self.project();
43        (this.func)(&item);
44        this.sink.start_send(item)
45    }
46    fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
47        self.project().sink.poll_flush(cx)
48    }
49    fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
50        self.project().sink.poll_close(cx)
51    }
52}
53
54/// [`SinkBuild`] for [`Inspect`].
55pub struct InspectBuilder<Prev, Func> {
56    pub(crate) prev: Prev,
57    pub(crate) func: Func,
58}
59impl<Prev, Func> SinkBuild for InspectBuilder<Prev, Func>
60where
61    Prev: SinkBuild,
62    Func: FnMut(&Prev::Item),
63{
64    type Item = Prev::Item;
65
66    type Output<Next: Sink<Prev::Item>> = Prev::Output<Inspect<Next, Func>>;
67
68    fn send_to<Next>(self, next: Next) -> Self::Output<Next>
69    where
70        Next: Sink<Prev::Item>,
71    {
72        self.prev.send_to(Inspect::new(self.func, next))
73    }
74}
sinktools/inspect.rs

sinktools/
inspect.rs
