im-util: Introduce helpers for ObservableVector2

eyeball-im-util/src/lib.rs

@@ -3,5 +3,7 @@
 //! The primary entry point of this library is [`VectorExt`].
 
 pub mod vector;
+pub mod vector2;
 
 pub use vector::VectorExt;
+pub use vector2::Vector2Ext;

eyeball-im-util/src/vector2.rs

@@ -0,0 +1,51 @@
+//! Utilities around [`ObservableVector`].
+
+use eyeball_im::{ObservableVector2, Vector, VectorSubscriber2};
+
+mod filter;
+
+pub use self::filter::{Filter, FilterMap};
+
+/// Extension trait for [`ObservableVector`].
+pub trait Vector2Ext<T>
+where
+    T: Clone + Send + Sync + 'static,
+{
+    /// Obtain a new subscriber that filters items by the given filter function.
+    ///
+    /// Returns a filtered version of the current vector, and a subscriber to
+    /// get updates through.
+    fn subscribe_filter<F>(&self, f: F) -> (Vector<T>, Filter<VectorSubscriber2<T>, F>)
+    where
+        F: Fn(&T) -> bool;
+
+    /// Obtain a new subscriber that filters and maps items with the given
+    /// function.
+    ///
+    /// Returns a filtered + mapped version of the current vector, and a
+    /// subscriber to get updates through.
+    fn subscribe_filter_map<U, F>(&self, f: F) -> (Vector<U>, FilterMap<VectorSubscriber2<T>, F>)
+    where
+        U: Clone,
+        F: Fn(T) -> Option<U>;
+}
+
+impl<T> Vector2Ext<T> for ObservableVector2<T>
+where
+    T: Clone + Send + Sync + 'static,
+{
+    fn subscribe_filter<F>(&self, f: F) -> (Vector<T>, Filter<VectorSubscriber2<T>, F>)
+    where
+        F: Fn(&T) -> bool,
+    {
+        Filter::new((*self).clone(), self.subscribe(), f)
+    }
+
+    fn subscribe_filter_map<U, F>(&self, f: F) -> (Vector<U>, FilterMap<VectorSubscriber2<T>, F>)
+    where
+        U: Clone,
+        F: Fn(T) -> Option<U>,
+    {
+        FilterMap::new((*self).clone(), self.subscribe(), f)
+    }
+}