Draft widget nodes and wire interaction

web/src/bus.rs

@@ -0,0 +1,40 @@
+use crate::Application;
+
+use std::rc::Rc;
+
+#[derive(Clone)]
+pub struct Bus<Message> {
+    publish: Rc<Box<dyn Fn(Message, &mut dyn dodrio::RootRender)>>,
+}
+
+impl<Message> Bus<Message>
+where
+    Message: 'static,
+{
+    pub fn new() -> Self {
+        Self {
+            publish: Rc::new(Box::new(|message, root| {
+                let app = root.unwrap_mut::<Application<Message>>();
+
+                app.update(message)
+            })),
+        }
+    }
+
+    pub fn publish(&self, message: Message, root: &mut dyn dodrio::RootRender) {
+        (self.publish)(message, root);
+    }
+
+    pub fn map<B>(&self, mapper: Rc<Box<dyn Fn(B) -> Message>>) -> Bus<B>
+    where
+        B: 'static,
+    {
+        let publish = self.publish.clone();
+
+        Bus {
+            publish: Rc::new(Box::new(move |message, root| {
+                publish(mapper(message), root)
+            })),
+        }
+    }
+}