Struct VacantEntry

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

Available on crate feature alloc only.

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

Implementations

impl<'a, K, V, A> VacantEntry<'a, K, V, A>

where K: Ord, A: Allocator + Clone,

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);

pub fn insert_entry(self, value: V) -> OccupiedEntry<'a, K, V, A>

🔬This is a nightly-only experimental API. (btree_entry_insert)

Sets the value of the entry with the VacantEntry’s key, and returns an OccupiedEntry.

Examples

#![feature(btree_entry_insert)]
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") {
    let entry = o.insert_entry(37);
    assert_eq!(entry.get(), &37);
}
assert_eq!(map["poneyland"], 37);

Trait Implementations

impl<K, V, A> Debug for VacantEntry<'_, K, V, A>

where K: Debug + Ord, A: Allocator + Clone,

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

Formats the value using the given formatter.