--- /dev/null
+use std::ops::Deref;
+use std::{hash, ptr};
+
+/// A wrapper around reference that compares and hashes like a pointer.
+/// Can be used as a key in sets/maps indexed by pointers to avoid `unsafe`.
+#[derive(Debug)]
+pub struct PtrKey<'a, T>(pub &'a T);
+
+impl<'a, T> Clone for PtrKey<'a, T> {
+ fn clone(&self) -> Self {
+ *self
+ }
+}
+
+impl<'a, T> Copy for PtrKey<'a, T> {}
+
+impl<'a, T> PartialEq for PtrKey<'a, T> {
+ fn eq(&self, rhs: &Self) -> bool {
+ ptr::eq(self.0, rhs.0)
+ }
+}
+
+impl<'a, T> Eq for PtrKey<'a, T> {}
+
+impl<'a, T> hash::Hash for PtrKey<'a, T> {
+ fn hash<H: hash::Hasher>(&self, hasher: &mut H) {
+ (self.0 as *const T).hash(hasher)
+ }
+}
+
+impl<'a, T> Deref for PtrKey<'a, T> {
+ type Target = T;
+
+ fn deref(&self) -> &Self::Target {
+ self.0
+ }
+}