pub trait MutableKeys {
    type Key;
    type Value;
    fn get_full_mut2<Q: ?Sized>(
        &mut self,
        key: &Q
    ) -> Option<(usize, &mut Self::Key, &mut Self::Value)>
        Q: Hash + Equivalent<Self::Key>
; fn retain2<F>(&mut self, keep: F)
        F: FnMut(&mut Self::Key, &mut Self::Value) -> bool
; fn __private_marker(&self) -> PrivateMarker; }
Expand description

Opt-in mutable access to keys.

These methods expose &mut K, mutable references to the key as it is stored in the map. You are allowed to modify the keys in the hashmap if the modifcation does not change the key’s hash and equality.

If keys are modified erronously, you can no longer look them up. This is sound (memory safe) but a logical error hazard (just like implementing PartialEq, Eq, or Hash incorrectly would be).

use this trait to enable its methods for IndexMap.

Associated Types

Required methods

Return item index, mutable reference to key and value

Scan through each key-value pair in the map and keep those where the closure keep returns true.

The elements are visited in order, and remaining elements keep their order.

Computes in O(n) time (average).

This method is not useful in itself – it is there to “seal” the trait for external implementation, so that we can add methods without causing breaking changes.


Opt-in mutable access to keys.

See MutableKeys for more information.