io_http/
coroutine.rs

1//! Generator-shape coroutine driver mirroring `core::ops::Coroutine`:
2//! `Yield` associated type for intermediate progress, `Return` for
3//! terminal output, and a two-variant [`HttpCoroutineState`]
4//! (`Yielded` / `Complete`).
5
6use alloc::vec::Vec;
7
8/// State yielded by an [`HttpCoroutine::resume`] step.
9#[derive(Debug)]
10pub enum HttpCoroutineState<Y, R> {
11    /// Intermediate step: the coroutine needs the caller to perform
12    /// the carried I/O request before the next resume.
13    Yielded(Y),
14    /// Terminal step: the coroutine is done and carries its final
15    /// output or error.
16    Complete(R),
17}
18
19/// Standard-shape HTTP coroutine: own internal state, declare per-step
20/// `Yield`, return `Result<Output, Error>` on completion.
21pub trait HttpCoroutine {
22    /// The intermediate value emitted on every yielded step.
23    type Yield;
24    /// The terminal value emitted on completion.
25    type Return;
26
27    /// Advances one step. Pass [`None`] initially or after [`HttpYield::WantsWrite`];
28    /// pass `Some(data)` after [`HttpYield::WantsRead`]; pass `Some(&[])` for EOF.
29    fn resume(&mut self, arg: Option<&[u8]>) -> HttpCoroutineState<Self::Yield, Self::Return>;
30}
31
32/// Standard I/O-only Yield; pick `type Yield = HttpYield` when the
33/// coroutine only reads or writes socket bytes.
34#[derive(Debug)]
35pub enum HttpYield {
36    /// The coroutine wants bytes read from the stream and handed back
37    /// on the next resume.
38    WantsRead,
39    /// The coroutine wants these bytes written to the stream.
40    WantsWrite(Vec<u8>),
41}
42
43/// Coroutine `?`: forwards `Yielded` (via `Into`), short-circuits on
44/// `Err` (via `Into`), evaluates to the inner `Ok` value.
45#[macro_export]
46macro_rules! http_try {
47    ($coroutine:expr, $arg:expr $(,)?) => {
48        match $crate::coroutine::HttpCoroutine::resume($coroutine, $arg) {
49            $crate::coroutine::HttpCoroutineState::Yielded(y) => {
50                return $crate::coroutine::HttpCoroutineState::Yielded(y.into());
51            }
52            $crate::coroutine::HttpCoroutineState::Complete(Err(err)) => {
53                return $crate::coroutine::HttpCoroutineState::Complete(Err(err.into()));
54            }
55            $crate::coroutine::HttpCoroutineState::Complete(Ok(value)) => value,
56        }
57    };
58}
io_http/coroutine.rs

io_http/
coroutine.rs
