Struct std::collections::btree_map::VacantEntry1.0.0 [] [src]

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

A vacant Entry. It is part of the Entry enum.

Methods

impl<'a, K, V> VacantEntry<'a, K, V> where K: Ord
[src]

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");Run

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();
}Run

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

Examples

use std::collections::BTreeMap;

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

// count the number of occurrences of letters in the vec
for x in vec!["a","b","a","c","a","b"] {
    *count.entry(x).or_insert(0) += 1;
}

assert_eq!(count["a"], 3);Run

Trait Implementations

impl<'a, K, V> Debug for VacantEntry<'a, K, V> where K: 'a + Ord + Debug, V: 'a
1.12.0
[src]

Formats the value using the given formatter.