Rename crate to NeXosim

nexosim-util/src/lib.rs

@@ -0,0 +1 @@
+pub mod observables;

nexosim-util/src/observables.rs

@@ -0,0 +1,96 @@
+//! Observable states.
+//!
+//! This module contains types used to implement states automatically propagated
+//! to output on change.
+//!
+
+use std::ops::Deref;
+
+use nexosim::ports::Output;
+
+/// Observability trait.
+pub trait Observable<T> {
+    /// Observe the value.
+    fn observe(&self) -> T;
+}
+
+impl<T> Observable<T> for T
+where
+    T: Clone,
+{
+    fn observe(&self) -> Self {
+        self.clone()
+    }
+}
+
+/// Observable state.
+///
+/// This object encapsulates state. Every state change is propagated to the
+/// output.
+#[derive(Debug)]
+pub struct ObservableState<S, T>
+where
+    S: Observable<T> + Default,
+    T: Clone + Send + 'static,
+{
+    /// State.
+    state: S,
+
+    /// Output used for observation.
+    out: Output<T>,
+}
+
+impl<S, T> ObservableState<S, T>
+where
+    S: Observable<T> + Default,
+    T: Clone + Send + 'static,
+{
+    /// New default state.
+    pub fn new(out: Output<T>) -> Self {
+        Self {
+            state: S::default(),
+            out,
+        }
+    }
+
+    /// Get state.
+    pub fn get(&self) -> &S {
+        &self.state
+    }
+
+    /// Set state.
+    pub async fn set(&mut self, value: S) {
+        self.state = value;
+        self.out.send(self.state.observe()).await;
+    }
+
+    /// Modify state using mutable reference.
+    pub async fn modify<F, R>(&mut self, f: F) -> R
+    where
+        F: FnOnce(&mut S) -> R,
+    {
+        let r = f(&mut self.state);
+        self.out.send(self.state.observe()).await;
+        r
+    }
+
+    /// Propagate value.
+    pub async fn propagate(&mut self) {
+        self.out.send(self.state.observe()).await;
+    }
+}
+
+impl<S, T> Deref for ObservableState<S, T>
+where
+    S: Observable<T> + Default,
+    T: Clone + Send + 'static,
+{
+    type Target = S;
+
+    fn deref(&self) -> &S {
+        &self.state
+    }
+}
+
+/// Observable value.
+pub type ObservableValue<T> = ObservableState<T, T>;