sinktools/
map.rs

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

sinktools/
map.rs
