wip: rewrite core to be template focused

packages/core/src/arena.rs

@@ -0,0 +1,30 @@
+use std::num::NonZeroUsize;
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
+pub struct ElementId(pub usize);
+
+// pub struct ElementId(pub NonZeroUsize);
+
+// impl Default for ElementId {
+//     fn default() -> Self {
+//         Self(NonZeroUsize::new(1).unwrap())
+//     }
+// }
+
+pub struct ElementArena {
+    counter: usize,
+}
+
+impl Default for ElementArena {
+    fn default() -> Self {
+        Self { counter: 1 }
+    }
+}
+
+impl ElementArena {
+    pub fn next(&mut self) -> ElementId {
+        let id = self.counter;
+        self.counter += 1;
+        ElementId(id)
+    }
+}