Struct alloc::collections::btree_map::OccupiedEntry

pub struct OccupiedEntry<'a, K, V, A: Allocator = Global> { /* private fields */ }

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

Implementations

impl<'a, K: Ord, V, A: Allocator> OccupiedEntry<'a, K, V, A>

pub fn key(&self) -> &K

Gets a reference to the key in the entry.

Examples

use std::collections::BTreeMap;

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

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

Take ownership of the key and value from the map.

Examples

use std::collections::BTreeMap;
use std::collections::btree_map::Entry;

let mut map: BTreeMap<&str, usize> = BTreeMap::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();
}

// If now try to get the value, it will panic:
// println!("{}", map["poneyland"]);

pub fn get(&self) -> &V

Gets a reference to the value in the entry.

Examples

use std::collections::BTreeMap;
use std::collections::btree_map::Entry;

let mut map: BTreeMap<&str, usize> = BTreeMap::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 that may outlive the destruction of the Entry value, see into_mut.

Examples

use std::collections::BTreeMap;
use std::collections::btree_map::Entry;

let mut map: BTreeMap<&str, usize> = BTreeMap::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 entry into a mutable reference to its value.

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

Examples

use std::collections::BTreeMap;
use std::collections::btree_map::Entry;

let mut map: BTreeMap<&str, usize> = BTreeMap::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 with the OccupiedEntry’s key, and returns the entry’s old value.

Examples

use std::collections::BTreeMap;
use std::collections::btree_map::Entry;

let mut map: BTreeMap<&str, usize> = BTreeMap::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 of the entry out of the map, and returns it.

Examples

use std::collections::BTreeMap;
use std::collections::btree_map::Entry;

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

if let Entry::Occupied(o) = map.entry("poneyland") {
    assert_eq!(o.remove(), 12);
}
// If we try to get "poneyland"'s value, it'll panic:
// println!("{}", map["poneyland"]);

Trait Implementations

impl<K: Debug + Ord, V: Debug, A: Allocator> Debug for OccupiedEntry<'_, K, V, A>

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

Formats the value using the given formatter.