singleton map

nested/src/singleton/map.rs

@@ -0,0 +1,84 @@
+use {
+    std::sync::Arc,
+    std::sync::RwLock,
+    crate::{
+        singleton::{SingletonView},
+        core::{
+            Observer, ObserverExt, ObserverBroadcast,
+            View, ViewPort, OuterViewPort
+        }
+    }
+};
+
+//<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>
+
+impl<Item: 'static> OuterViewPort<dyn SingletonView<Item = Item>> {
+    pub fn map<
+        DstItem: 'static,
+        F: Fn(Item) -> DstItem + Send + Sync + 'static
+    >(
+        &self,
+        f: F
+    ) -> OuterViewPort<dyn SingletonView<Item = DstItem>> {
+        let port = ViewPort::new();
+        port.add_update_hook(Arc::new(self.0.clone()));
+
+        let map = Arc::new(RwLock::new(MapSingleton {
+            src_view: None,
+            f,
+            cast: port.inner().get_broadcast()
+        }));
+
+        self.add_observer(map.clone());
+        port.inner().set_view(Some(map));
+        port.into_outer()
+    }
+}
+
+//<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>
+
+pub struct MapSingleton<DstItem, SrcView, F>
+where SrcView: SingletonView + ?Sized,
+      F: Fn(SrcView::Item) -> DstItem + Send + Sync
+{
+    src_view: Option<Arc<SrcView>>,
+    f: F,
+    cast: Arc<RwLock<ObserverBroadcast<dyn SingletonView<Item = DstItem>>>>
+}
+
+//<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>
+
+impl<DstItem, SrcView, F> View for MapSingleton<DstItem, SrcView, F>
+where SrcView: SingletonView + ?Sized,
+      F: Fn(SrcView::Item) -> DstItem + Send + Sync
+{
+    type Msg = ();
+}
+
+impl<DstItem, SrcView, F> SingletonView for MapSingleton<DstItem, SrcView, F>
+where SrcView: SingletonView + ?Sized,
+      F: Fn(SrcView::Item) -> DstItem + Send + Sync
+{
+    type Item = DstItem;
+
+    fn get(&self) -> DstItem {
+        (self.f)(self.src_view.as_ref().unwrap().get())
+    }
+}
+
+//<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>
+
+impl<DstItem, SrcView, F> Observer<SrcView> for MapSingleton<DstItem, SrcView, F>
+where SrcView: SingletonView + ?Sized,
+      F: Fn(SrcView::Item) -> DstItem + Send + Sync
+{
+    fn reset(&mut self, view: Option<Arc<SrcView>>) {
+        self.src_view = view;
+        self.cast.notify(&());
+    }
+
+    fn notify(&mut self, msg: &()) {
+        self.cast.notify(msg);
+    }
+}
+

nested/src/singleton/mod.rs

@@ -1,5 +1,6 @@
 
 pub mod buffer;
+pub mod map;
 
 use {
     std::{