learn how workspaces + proc macros work & restructure everything

core/src/util/arena.rs

@@ -0,0 +1,109 @@
+use std::ops::Deref;
+
+use crate::util::{Id, IdNum, IdTracker};
+
+pub struct Arena<T, I> {
+    data: Vec<T>,
+    tracker: IdTracker<I>,
+}
+
+impl<T, I: IdNum> Arena<T, I> {
+    pub fn new() -> Self {
+        Self {
+            data: Vec::new(),
+            tracker: IdTracker::default(),
+        }
+    }
+
+    pub fn push(&mut self, value: T) -> Id<I> {
+        let id = self.tracker.next();
+        let i = id.idx();
+        if i == self.data.len() {
+            self.data.push(value);
+        } else {
+            self.data[i] = value;
+        }
+        id
+    }
+
+    pub fn remove(&mut self, id: Id<I>) -> T
+    where
+        T: Copy,
+    {
+        let i = id.idx();
+        self.tracker.free(id);
+        self.data[i]
+    }
+}
+
+impl<T, I: IdNum> Default for Arena<T, I> {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+pub struct TrackedArena<T, I> {
+    inner: Arena<T, I>,
+    refs: Vec<u32>,
+    pub changed: bool,
+}
+
+impl<T, I: IdNum> TrackedArena<T, I> {
+    pub fn new() -> Self {
+        Self {
+            inner: Arena::default(),
+            refs: Vec::new(),
+            changed: true,
+        }
+    }
+
+    pub fn push(&mut self, value: T) -> Id<I> {
+        self.changed = true;
+        let id = self.inner.push(value);
+        let i = id.idx();
+        if i == self.refs.len() {
+            self.refs.push(0);
+        }
+        id
+    }
+
+    pub fn push_ref(&mut self, i: Id<I>) {
+        self.refs[i.idx()] += 1;
+    }
+
+    pub fn remove(&mut self, id: Id<I>) -> T
+    where
+        T: Copy,
+    {
+        let i = id.idx();
+        self.refs[i] -= 1;
+        if self.refs[i] == 0 {
+            self.changed = true;
+            self.inner.remove(id)
+        } else {
+            self[i]
+        }
+    }
+}
+
+impl<T, I: IdNum> Default for TrackedArena<T, I> {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl<T, I> Deref for TrackedArena<T, I> {
+    type Target = Vec<T>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.inner.data
+    }
+}
+
+impl<T, I> Deref for Arena<T, I> {
+    type Target = Vec<T>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.data
+    }
+}