head-management: add infrastructure

src/utils/copyhashmap.rs

@@ -66,6 +66,14 @@ impl<K: Eq + Hash, V> CopyHashMap<K, V> {
         unsafe { self.map.get().deref().contains_key(k) }
     }
 
+    pub fn not_contains<Q>(&self, k: &Q) -> bool
+    where
+        Q: Hash + Eq + ?Sized,
+        K: Borrow<Q>,
+    {
+        !self.contains(k)
+    }
+
     pub fn lock(&self) -> Locked<'_, K, V> {
         Locked {
             source: self,

src/utils/rc_eq.rs

@@ -1,5 +1,29 @@
-use std::rc::Rc;
+use std::{ops::Deref, rc::Rc};
 
 pub fn rc_eq<T: ?Sized>(a: &Rc<T>, b: &Rc<T>) -> bool {
     Rc::as_ptr(a) as *const u8 == Rc::as_ptr(b) as *const u8
 }
+
+pub struct RcEq<T>(pub Rc<T>);
+
+impl<T> Clone for RcEq<T> {
+    fn clone(&self) -> Self {
+        Self(self.0.clone())
+    }
+}
+
+impl<T> PartialEq for RcEq<T> {
+    fn eq(&self, other: &Self) -> bool {
+        rc_eq(&self.0, &other.0)
+    }
+}
+
+impl<T> Eq for RcEq<T> {}
+
+impl<T> Deref for RcEq<T> {
+    type Target = T;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}