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dfir_pipes/pull/
inspect.rs

1use core::pin::Pin;
2
3use pin_project_lite::pin_project;
4
5use crate::pull::{FusedPull, Pull, PullStep};
6
7pin_project! {
8    /// Pull combinator that calls a closure on each item for side effects, passing the item through.
9    #[must_use = "`Pull`s do nothing unless polled"]
10    #[derive(Clone, Debug)]
11    pub struct Inspect<Prev, Func> {
12        #[pin]
13        prev: Prev,
14        func: Func,
15    }
16}
17
18impl<Prev, Func> Inspect<Prev, Func>
19where
20    Self: Pull,
21{
22    pub(crate) const fn new(prev: Prev, func: Func) -> Self {
23        Self { prev, func }
24    }
25}
26
27impl<Prev, Func> Pull for Inspect<Prev, Func>
28where
29    Prev: Pull,
30    Func: FnMut(&Prev::Item),
31{
32    type Ctx<'ctx> = Prev::Ctx<'ctx>;
33
34    type Item = Prev::Item;
35    type Meta = Prev::Meta;
36    type CanPend = Prev::CanPend;
37    type CanEnd = Prev::CanEnd;
38
39    fn pull(
40        self: Pin<&mut Self>,
41        ctx: &mut Self::Ctx<'_>,
42    ) -> PullStep<Self::Item, Self::Meta, Self::CanPend, Self::CanEnd> {
43        let this = self.project();
44        match this.prev.pull(ctx) {
45            PullStep::Ready(item, meta) => {
46                (this.func)(&item);
47                PullStep::Ready(item, meta)
48            }
49            PullStep::Pending(can_pend) => PullStep::Pending(can_pend),
50            PullStep::Ended(can_end) => PullStep::Ended(can_end),
51        }
52    }
53
54    fn size_hint(&self) -> (usize, Option<usize>) {
55        self.prev.size_hint()
56    }
57}
58
59impl<Prev, Func> FusedPull for Inspect<Prev, Func>
60where
61    Prev: FusedPull,
62    Func: FnMut(&Prev::Item),
63{
64}