intrepid-core 0.1.2

Manage complex async business logic with ease
Documentation 
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use std::convert::Infallible;

use crate::Frame;

use super::{ExtractContext, Extractor};

/// Retrieve the state an action expects. This has the side-effect of creating a
/// state dependency for the action. All actions in a given system must share the
/// same state type.
///
#[derive(Clone)]
pub struct State<T: Clone>(pub T);

impl<StateContents> Extractor<StateContents> for State<StateContents>
where
    StateContents: Clone + Send + Sync,
{
    type Error = Infallible;

    fn extract(_: Frame, (_, state): &ExtractContext<StateContents>) -> Result<Self, Self::Error> {
        Ok(State(state.clone()))
    }
}

impl<State> Extractor<State> for () {
    type Error = Infallible;

    fn extract(_: Frame, _: &ExtractContext<State>) -> Result<Self, Self::Error> {
        Ok(())
    }
}

#[test]
fn extract_state_from_frame() {
    use crate::ActionContext;

    let state = 42;
    let frame = Frame::default();
    let extracted = State::extract(frame, &(ActionContext::default(), state)).unwrap();

    assert_eq!(extracted.0, 42);
}