orga 0.1.10

State machine engine
Documentation 
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use super::State;
use crate::error::Result;
use crate::store::{Read, Store};
use std::ops::{Deref, DerefMut};

/// A `State` implementation which exposes the underlying raw store (itself
/// implementing `Store`). If the underlying store is only `Read`, then the
/// `WrapperStore` will only implement `Read`.
///
/// This can be useful when composing `State` types into a hierarchy, when
/// access to the raw `Store` API is still necessary.
pub struct WrapperStore<S: Read>(S);

impl<S: Read> State<S> for WrapperStore<S> {
    fn wrap_store(store: S) -> Result<WrapperStore<S>> {
        Ok(WrapperStore(store))
    }
}

impl<S: Read> Deref for WrapperStore<S> {
    type Target = S;
    fn deref(&self) -> &S {
        &self.0
    }
}

impl<S: Store> DerefMut for WrapperStore<S> {
    fn deref_mut(&mut self) -> &mut S {
        &mut self.0
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::store::*;

    #[test]
    fn simple() {
        let mut store = MapStore::new();
        let mut wrapper: WrapperStore<_> = (&mut store).wrap().unwrap();

        assert_eq!(wrapper.get(&[0]).unwrap(), None);
        wrapper.put(vec![0], vec![1]).unwrap();
        assert_eq!(wrapper.get(&[0]).unwrap(), Some(vec![1]));
        assert_eq!(store.get(&[0]).unwrap(), Some(vec![1]));
    }

    #[test]
    fn read_only() {
        let mut store = MapStore::new();
        let mut wrapper: WrapperStore<_> = (&mut store).wrap().unwrap();
        wrapper.put(vec![0], vec![1]).unwrap();

        let store = store;
        let wrapper: WrapperStore<_> = store.wrap().unwrap();
        assert_eq!(wrapper.get(&[0]).unwrap(), Some(vec![1]));
    }
}