diff --git a/src/mono_hash_map.rs b/src/mono_hash_map.rs index 278bbd9cf2b1..ec1a5fdb4288 100644 --- a/src/mono_hash_map.rs +++ b/src/mono_hash_map.rs @@ -18,8 +18,16 @@ use crate::AllocMap; pub struct MonoHashMap(RefCell>>); impl MonoHashMap { - pub fn values(&self, f: impl FnOnce(&mut dyn Iterator) -> T) -> T { - f(&mut self.0.borrow().values().map(|v| &**v)) + /// This function exists for priroda to be able to iterate over all evaluator memory + /// + /// The function is somewhat roundabout with the closure argument because internally the + /// `MonoHashMap` uses a `RefCell`. When iterating over the `HashMap` inside the `RefCell`, + /// we need to keep a borrow to the `HashMap` inside the iterator. The borrow is only alive + /// as long as the `Ref` returned by `RefCell::borrow()` is alive. So we can't return the + /// iterator, as that would drop the `Ref`. We can't return both, as it's not possible in Rust + /// to have a struct/tuple with a field that refers to another field. + pub fn iter(&self, f: impl FnOnce(&mut dyn Iterator) -> T) -> T { + f(&mut self.0.borrow().iter().map(|(k, v)| (k, &**v))) } }