1 use {
2     bindings::{
3         exports::local::local::short_reads::{self, Guest, GuestThing},
4         wit_stream,
5     },
6     wit_bindgen::{StreamReader, StreamResult, rt::async_support},
7 };
8 
9 mod bindings {
10     wit_bindgen::generate!({
11         path: "../misc/component-async-tests/wit",
12         world: "short-reads-guest",
13     });
14 
15     use super::Component;
16     export!(Component);
17 }
18 
19 struct Thing {
20     value: String,
21 }
22 
23 impl GuestThing for Thing {
24     fn new(value: String) -> Self {
25         Self { value }
26     }
27 
28     async fn get(&self) -> String {
29         self.value.clone()
30     }
31 }
32 
33 struct Component;
34 
35 impl Guest for Component {
36     type Thing = Thing;
37 
38     async fn short_reads(
39         mut stream: StreamReader<short_reads::Thing>,
40     ) -> StreamReader<short_reads::Thing> {
41         let (mut tx, rx) = wit_stream::new();
42 
43         async_support::spawn(async move {
44             // Read the things one at a time, forcing the host to re-take
45             // ownership of any unwritten items between writes.
46             let mut things = Vec::new();
47             loop {
48                 let (status, buffer) = stream.read(Vec::with_capacity(1)).await;
49                 match status {
50                     StreamResult::Complete(_) => {
51                         things.extend(buffer);
52                     }
53                     StreamResult::Dropped => break,
54                     StreamResult::Cancelled => unreachable!(),
55                 }
56             }
57             // Write the things all at once.  The host will read them only one
58             // at a time, forcing us to re-take ownership of any unwritten
59             // items between writes.
60             things = tx.write_all(things).await;
61             assert!(things.is_empty());
62         });
63 
64         rx
65     }
66 }
67 
68 // Unused function; required since this file is built as a `bin`:
69 fn main() {}
70