rocket/response/stream/
text.rs

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1use futures::stream::{Stream, StreamExt};
2
3use crate::request::Request;
4use crate::response::{self, Response, Responder};
5use crate::http::ContentType;
6use crate::response::stream::ReaderStream;
7
8/// A potentially infinite stream of text: `T: AsRef<str>`.
9///
10/// A `TextStream` can be constructed from any [`Stream`] of items of type `T`
11/// where `T: AsRef<str>`. This includes `&str`, `String`, `Cow<str>`,
12/// `&RawStr`, and more. The stream can be constructed directly, via
13/// `TextStream(..)` or [`TextStream::from()`], or through generator syntax via
14/// [`TextStream!`].
15///
16/// [`Stream`]: https://docs.rs/futures/0.3/futures/stream/trait.Stream.html
17///
18/// # Responder
19///
20/// `TextStream` is a (potentially infinite) responder. The response
21/// `Content-Type` is set to [`Text`](ContentType::Text). The body is
22/// [unsized](crate::response::Body#unsized), and values are sent as soon as
23/// they are yielded by the internal iterator.
24///
25/// # Example
26///
27/// Use [`TextStream!`] to yield 10 strings, one every second, of the form `"n:
28/// $k"` for `$k` from `0` to `10` exclusive:
29///
30/// ```rust
31/// # use rocket::*;
32/// use rocket::response::stream::TextStream;
33/// use rocket::futures::stream::{repeat, StreamExt};
34/// use rocket::tokio::time::{self, Duration};
35///
36/// #[get("/text")]
37/// fn text() -> TextStream![&'static str] {
38///     TextStream(repeat("hi"))
39/// }
40///
41/// #[get("/text/stream")]
42/// fn stream() -> TextStream![String] {
43///     TextStream! {
44///         let mut interval = time::interval(Duration::from_secs(1));
45///         for i in 0..10 {
46///             yield format!("n: {}", i);
47///             interval.tick().await;
48///         }
49///     }
50/// }
51/// ```
52///
53/// The syntax of [`TextStream!`] as an expression is identical to that of
54/// [`stream!`](crate::response::stream::stream).
55#[derive(Debug, Clone)]
56pub struct TextStream<S>(pub S);
57
58impl<S> From<S> for TextStream<S> {
59    /// Creates a `TextStream` from any `S: Stream`.
60    fn from(stream: S) -> Self {
61        TextStream(stream)
62    }
63}
64
65impl<'r, S: Stream> Responder<'r, 'r> for TextStream<S>
66    where S: Send + 'r, S::Item: AsRef<str> + Send + Unpin + 'r
67{
68    fn respond_to(self, _: &'r Request<'_>) -> response::Result<'r> {
69        struct ByteStr<T>(T);
70
71        impl<T: AsRef<str>> AsRef<[u8]> for ByteStr<T> {
72            fn as_ref(&self) -> &[u8] {
73                self.0.as_ref().as_bytes()
74            }
75        }
76
77        let inner = self.0.map(ByteStr).map(std::io::Cursor::new);
78        Response::build()
79            .header(ContentType::Text)
80            .streamed_body(ReaderStream::from(inner))
81            .ok()
82    }
83}
84
85crate::export! {
86    /// Type and stream expression macro for [`struct@TextStream`].
87    ///
88    /// See [`stream!`](crate::response::stream::stream) for the syntax
89    /// supported by this macro.
90    ///
91    /// See [`struct@TextStream`] and the [module level
92    /// docs](crate::response::stream#typed-streams) for usage details.
93    macro_rules! TextStream {
94        ($($s:tt)*) => ($crate::_typed_stream!(TextStream, $($s)*));
95    }
96}
rocket/response/stream/text.rs

rocket/response/stream/
text.rs
