Struct std::collections::hash_map::VacantEntry

pub struct VacantEntry<'a, K: 'a, V: 'a> {
    // some fields omitted
}

A view into a single empty location in a HashMap. It is part of the Entry enum.

Methods

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

fn key(&self) -> &K

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

Examples

fn main() { use std::collections::HashMap; let mut map: HashMap<&str, u32> = HashMap::new(); assert_eq!(map.entry("poneyland").key(), &"poneyland"); }

use std::collections::HashMap;

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

fn into_key(self) -> K

Unstable (map_entry_recover_keys #34285)

Take ownership of the key.

Examples

#![feature(map_entry_recover_keys)] fn main() { use std::collections::HashMap; use std::collections::hash_map::Entry; let mut map: HashMap<&str, u32> = HashMap::new(); if let Entry::Vacant(v) = map.entry("poneyland") { v.into_key(); } }

#![feature(map_entry_recover_keys)]

use std::collections::HashMap;
use std::collections::hash_map::Entry;

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

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

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

fn main() { use std::collections::HashMap; use std::collections::hash_map::Entry; let mut map: HashMap<&str, u32> = HashMap::new(); if let Entry::Vacant(o) = map.entry("poneyland") { o.insert(37); } assert_eq!(map["poneyland"], 37); }

use std::collections::HashMap;
use std::collections::hash_map::Entry;

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

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

Trait Implementations

impl<'a, K: 'a + Debug, V: 'a> Debug for VacantEntry<'a, K, V>

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

Formats the value using the given formatter.