add the ability to map signals

packages/signals/tests/map.rs

@@ -0,0 +1,32 @@
+#![allow(unused, non_upper_case_globals, non_snake_case)]
+
+use dioxus::prelude::*;
+use dioxus_core::ElementId;
+use dioxus_signals::*;
+
+#[test]
+fn create_signals_global() {
+    let mut dom = VirtualDom::new(|cx| {
+        render! {
+            for _ in 0..10 {
+                Child {}
+            }
+        }
+    });
+
+    fn Child(cx: Scope) -> Element {
+        let signal = create_without_cx();
+        let mapped = SignalMap::new(signal, |v| v.as_bytes());
+
+        render! {
+            "{signal:?}"
+            "{mapped:?}"
+        }
+    }
+
+    let _edits = dom.rebuild().santize();
+
+    fn create_without_cx() -> Signal<String> {
+        Signal::new("hello world".to_string())
+    }
+}