Struct OccupiedError

pub struct OccupiedError<'a, K, V, S, A = Global>
where
    A: Allocator,
{
    pub entry: OccupiedEntry<'a, K, V, S, A>,
    pub value: V,
}

The error returned by try_insert when the key already exists.

Contains the occupied entry, and the value that was not inserted.

Examples

use hashbrown::hash_map::{HashMap, OccupiedError};

let mut map: HashMap<_, _> = [("a", 10), ("b", 20)].into();

// try_insert method returns mutable reference to the value if keys are vacant,
// but if the map did have key present, nothing is updated, and the provided
// value is returned inside `Err(_)` variant
match map.try_insert("a", 100) {
    Err(OccupiedError { mut entry, value }) => {
        assert_eq!(entry.key(), &"a");
        assert_eq!(value, 100);
        assert_eq!(entry.insert(100), 10)
    }
    _ => unreachable!(),
}
assert_eq!(map[&"a"], 100);

Fields

entry: OccupiedEntry<'a, K, V, S, A>

The entry in the map that was already occupied.

value: V

The value which was not inserted, because the entry was already occupied.

Trait Implementations

impl<K, V, S, A> Debug for OccupiedError<'_, K, V, S, A>

where K: Debug, V: Debug, A: Allocator,

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<'a, K, V, S, A> Display for OccupiedError<'a, K, V, S, A>

where K: Debug, V: Debug, A: Allocator,

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.