rust-elm 0.9.0

Elm Architecture for Rust: composable reducers, pure effects, async runtime.
Documentation 
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//! Shared state lock helpers for [`Mutex`](parking_lot::Mutex) and [`RwLock`](parking_lot::RwLock) stores.

use std::sync::Arc;

use parking_lot::{Mutex, RwLock};

pub(crate) trait StateRead<S> {
    fn with_read<R>(&self, f: impl FnOnce(&S) -> R) -> R;
}

pub(crate) trait StateWrite<S>: StateRead<S> {
    fn with_write<R>(&self, f: impl FnOnce(&mut S) -> R) -> R;
}

impl<S> StateRead<S> for Arc<Mutex<S>> {
    fn with_read<R>(&self, f: impl FnOnce(&S) -> R) -> R {
        f(&*self.lock())
    }
}

impl<S> StateWrite<S> for Arc<Mutex<S>> {
    fn with_write<R>(&self, f: impl FnOnce(&mut S) -> R) -> R {
        f(&mut *self.lock())
    }
}

impl<S> StateRead<S> for Arc<RwLock<S>> {
    fn with_read<R>(&self, f: impl FnOnce(&S) -> R) -> R {
        f(&*self.read())
    }
}

impl<S> StateWrite<S> for Arc<RwLock<S>> {
    fn with_write<R>(&self, f: impl FnOnce(&mut S) -> R) -> R {
        f(&mut *self.write())
    }
}

#[cfg(feature = "arc-swap")]
use arc_swap::ArcSwap;

/// Lock-free snapshot load from [`ArcSwap`] (see `arc-swap` feature).
#[cfg(feature = "arc-swap")]
pub(crate) trait SnapshotRead<S> {
    fn with_snapshot<R>(&self, f: impl FnOnce(&S) -> R) -> R;

    fn load_snapshot(&self) -> Arc<S>;
}

#[cfg(feature = "arc-swap")]
impl<S> SnapshotRead<S> for Arc<ArcSwap<S>> {
    fn with_snapshot<R>(&self, f: impl FnOnce(&S) -> R) -> R {
        f(&*self.load_full())
    }

    fn load_snapshot(&self) -> Arc<S> {
        self.load_full()
    }
}