Struct OccupiedEntry

pub struct OccupiedEntry<'a, K, V, const N: usize, S>(/* private fields */);

A view into an occupied entry in a HashMap. It is part of the Entry enum.

Implementations

impl<'a, K, V, const N: usize, S> OccupiedEntry<'a, K, V, N, S>

pub fn key(&self) -> &K

Gets a reference to the key in the entry.

Examples

use halfbrown::HashMap;

let mut map: HashMap<&str, u32> = HashMap::new();
map.entry("poneyland").or_insert(12);
assert_eq!(map.entry("poneyland").key(), &"poneyland");

pub fn remove_entry(self) -> (K, V)

Take the ownership of the key and value from the map.

Examples

use halfbrown::HashMap;
use halfbrown::Entry;

let mut map: HashMap<&str, u32> = HashMap::new();
map.entry("poneyland").or_insert(12);

if let Entry::Occupied(o) = map.entry("poneyland") {
    // We delete the entry from the map.
    o.remove_entry();
}

assert_eq!(map.contains_key("poneyland"), false);

pub fn get(&self) -> &V

Gets a reference to the value in the entry.

Examples

use halfbrown::HashMap;
use halfbrown::Entry;

let mut map: HashMap<&str, u32> = HashMap::new();
map.entry("poneyland").or_insert(12);

if let Entry::Occupied(o) = map.entry("poneyland") {
    assert_eq!(o.get(), &12);
}

pub fn get_mut(&mut self) -> &mut V

Gets a mutable reference to the value in the entry.

If you need a reference to the OccupiedEntry which may outlive the destruction of the Entry value, see into_mut.

Examples

use halfbrown::HashMap;
use halfbrown::Entry;

let mut map: HashMap<&str, u32> = HashMap::new();
map.entry("poneyland").or_insert(12);

assert_eq!(map["poneyland"], 12);
if let Entry::Occupied(mut o) = map.entry("poneyland") {
    *o.get_mut() += 10;
    assert_eq!(*o.get(), 22);

    // We can use the same Entry multiple times.
    *o.get_mut() += 2;
}

assert_eq!(map["poneyland"], 24);

pub fn into_mut(self) -> &'a mut V

Converts the OccupiedEntry into a mutable reference to the value in the entry with a lifetime bound to the map itself.

If you need multiple references to the OccupiedEntry, see get_mut.

Examples

use halfbrown::HashMap;
use halfbrown::Entry;

let mut map: HashMap<&str, u32> = HashMap::new();
map.entry("poneyland").or_insert(12);

assert_eq!(map["poneyland"], 12);
if let Entry::Occupied(o) = map.entry("poneyland") {
    *o.into_mut() += 10;
}

assert_eq!(map["poneyland"], 22);

pub fn insert(&mut self, value: V) -> V

Sets the value of the entry, and returns the entry’s old value.

Examples

use halfbrown::HashMap;
use halfbrown::Entry;

let mut map: HashMap<&str, u32> = HashMap::new();
map.entry("poneyland").or_insert(12);

if let Entry::Occupied(mut o) = map.entry("poneyland") {
    assert_eq!(o.insert(15), 12);
}

assert_eq!(map["poneyland"], 15);

pub fn remove(self) -> V

Takes the value out of the entry, and returns it.

Examples

use halfbrown::HashMap;
use halfbrown::Entry;

let mut map: HashMap<&str, u32> = HashMap::new();
map.entry("poneyland").or_insert(12);

if let Entry::Occupied(o) = map.entry("poneyland") {
    assert_eq!(o.remove(), 12);
}

assert_eq!(map.contains_key("poneyland"), false);

pub fn replace_entry_with<F>(self, f: F) -> Entry<'a, K, V, N, S>

where F: FnOnce(&K, V) -> Option<V>, V: Clone,

Replaces the entry, returning the old key and value. The new key in the hash map will be the key used to create this entry.

Examples

use halfbrown::{Entry, HashMap};
use std::rc::Rc;

let mut map: HashMap<&str, u32> = HashMap::new();
map.insert("poneyland", 42);

let entry = match map.entry("poneyland") {
    Entry::Occupied(e) => {
        e.replace_entry_with(|k, v| {
            assert_eq!(k, &"poneyland");
            assert_eq!(v, 42);
            Some(v + 1)
        })
    }
    Entry::Vacant(_) => panic!(),
};

match entry {
    Entry::Occupied(e) => {
        assert_eq!(e.key(), &"poneyland");
        assert_eq!(e.get(), &43);
    }
    Entry::Vacant(_) => panic!(),
}

assert_eq!(map["poneyland"], 43);

let entry = match map.entry("poneyland") {
    Entry::Occupied(e) => e.replace_entry_with(|_k, _v| None),
    Entry::Vacant(_) => panic!(),
};

match entry {
    Entry::Vacant(e) => {
        assert_eq!(e.key(), &"poneyland");
    }
    Entry::Occupied(_) => panic!(),
}

assert!(!map.contains_key("poneyland"));

Trait Implementations

impl<K: Debug, V: Debug, const N: usize, S> Debug for OccupiedEntry<'_, K, V, N, S>

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

Formats the value using the given formatter.

impl<K, V, const N: usize, S> Send for OccupiedEntry<'_, K, V, N, S>

where K: Send, V: Send, S: Send,

impl<K, V, const N: usize, S> Sync for OccupiedEntry<'_, K, V, N, S>

where K: Sync, V: Sync, S: Sync,