intrepid_core/extract/
state.rs

1use std::convert::Infallible;
2
3use crate::{Context, Frame, StateNotReadyError};
4
5use super::Extractor;
6
7/// Retrieve the state an action expects. This has the side-effect of creating a
8/// state dependency for the action. All actions in a given system must share the
9/// same state type.
10///
11#[derive(Clone)]
12pub struct State<T: Clone>(pub T);
13
14impl<StateContents> Extractor<StateContents> for State<StateContents>
15where
16    StateContents: Clone + Send + Sync,
17{
18    type Error = StateNotReadyError;
19
20    fn extract(_: Frame, context: &Context<StateContents>) -> Result<Self, Self::Error> {
21        Ok(State(context.state()?))
22    }
23}
24
25impl<State> Extractor<State> for () {
26    type Error = Infallible;
27
28    fn extract(_: Frame, _: &Context<State>) -> Result<Self, Self::Error> {
29        Ok(())
30    }
31}
32
33#[test]
34fn extract_state_from_frame() {
35    let state = 42;
36    let frame = Frame::default();
37    let context = Context::from(state);
38    let extracted = State::extract(frame, &context).unwrap();
39
40    assert_eq!(extracted.0, 42);
41}
intrepid_core/extract/state.rs

intrepid_core/extract/
state.rs
