Enum std::collections::btree_map::Entry1.0.0 [] [src]

pub enum Entry<'a, K, V> where
    K: 'a,
    V: 'a, 
{ Vacant(VacantEntry<'a, K, V>), Occupied(OccupiedEntry<'a, K, V>), }

A view into a single entry in a map, which may either be vacant or occupied.

This enum is constructed from the entry method on BTreeMap.

Variants

A vacant entry.

An occupied entry.

Methods

impl<'a, K, V> Entry<'a, K, V> where
    K: Ord
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Important traits for &'a mut I
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Ensures a value is in the entry by inserting the default if empty, and returns a mutable reference to the value 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["poneyland"], 12);Run

Important traits for &'a mut I
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Ensures a value is in the entry by inserting the result of the default function if empty, and returns a mutable reference to the value in the entry.

Examples

use std::collections::BTreeMap;

let mut map: BTreeMap<&str, String> = BTreeMap::new();
let s = "hoho".to_string();

map.entry("poneyland").or_insert_with(|| s);

assert_eq!(map["poneyland"], "hoho".to_string());Run

Important traits for &'a mut I
1.10.0
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Returns a reference to this entry's key.

Examples

use std::collections::BTreeMap;

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

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🔬 This is a nightly-only experimental API. (entry_and_modify #44733)

Provides in-place mutable access to an occupied entry before any potential inserts into the map.

Examples

#![feature(entry_and_modify)]
use std::collections::BTreeMap;

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

map.entry("poneyland")
   .and_modify(|e| { *e += 1 })
   .or_insert(42);
assert_eq!(map["poneyland"], 42);

map.entry("poneyland")
   .and_modify(|e| { *e += 1 })
   .or_insert(42);
assert_eq!(map["poneyland"], 43);Run

impl<'a, K, V> Entry<'a, K, V> where
    K: Ord,
    V: Default
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Important traits for &'a mut I
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🔬 This is a nightly-only experimental API. (entry_or_default #44324)

Ensures a value is in the entry by inserting the default value if empty, and returns a mutable reference to the value in the entry.

Examples

#![feature(entry_or_default)]
use std::collections::BTreeMap;

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

assert_eq!(map["poneyland"], None);Run

Trait Implementations

impl<'a, K, V> Debug for Entry<'a, K, V> where
    K: 'a + Ord + Debug,
    V: 'a + Debug
1.12.0
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Formats the value using the given formatter. Read more