Struct alloc::collections::btree::map::entry::VacantEntry

pub struct VacantEntry<'a, K, V, A: Allocator + Clone = Global> {
    pub(super) key: K,
    pub(super) handle: Option<Handle<NodeRef<Mut<'a>, K, V, Leaf>, Edge>>,
    pub(super) dormant_map: DormantMutRef<'a, BTreeMap<K, V, A>>,
    pub(super) alloc: A,
    pub(super) _marker: PhantomData<&'a mut (K, V)>,
}

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

Fields

key: K

handle: Option<Handle<NodeRef<Mut<'a>, K, V, Leaf>, Edge>>

None for a (empty) map without root

dormant_map: DormantMutRef<'a, BTreeMap<K, V, A>>

alloc: A

The BTreeMap will outlive this IntoIter so we don’t care about drop order for alloc.

_marker: PhantomData<&'a mut (K, V)>

Implementations

impl<'a, K: Ord, V, A: Allocator + Clone> VacantEntry<'a, K, V, A>

pub fn key(&self) -> &K

Gets a reference to the key that would be used when inserting a value through the VacantEntry.

Examples

use std::collections::BTreeMap;

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

pub fn into_key(self) -> K

Take ownership of the key.

Examples

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

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

if let Entry::Vacant(v) = map.entry("poneyland") {
    v.into_key();
}

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

Sets the value of the entry with the VacantEntry’s key, and returns a mutable reference to it.

Examples

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

let mut map: BTreeMap<&str, u32> = BTreeMap::new();

if let Entry::Vacant(o) = map.entry("poneyland") {
    o.insert(37);
}
assert_eq!(map["poneyland"], 37);

Trait Implementations

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

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

Formats the value using the given formatter.