rustc_hir::def_id

Type Alias DefIdMapEntry

Source
pub type DefIdMapEntry<'a, T> = Entry<'a, DefId, T>;

Aliased Type§

enum DefIdMapEntry<'a, T> {
    Occupied(OccupiedEntry<'a, DefId, T>),
    Vacant(VacantEntry<'a, DefId, T>),
}

Variants§

§

Occupied(OccupiedEntry<'a, DefId, T>)

An occupied entry.

§

Vacant(VacantEntry<'a, DefId, T>)

A vacant entry.

Layout§

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 24 bytes

Size for each variant:

  • Occupied: 24 bytes
  • Vacant: 24 bytes

Implementations

Source§

impl<'a, K, V> Entry<'a, K, V>

1.0.0 · Source

pub fn or_insert(self, default: V) -> &'a mut V

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::HashMap;

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

map.entry("poneyland").or_insert(3);
assert_eq!(map["poneyland"], 3);

*map.entry("poneyland").or_insert(10) *= 2;
assert_eq!(map["poneyland"], 6);
1.0.0 · Source

pub fn or_insert_with<F>(self, default: F) -> &'a mut V
where F: FnOnce() -> V,

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::HashMap;

let mut map = HashMap::new();
let value = "hoho";

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

assert_eq!(map["poneyland"], "hoho");
1.50.0 · Source

pub fn or_insert_with_key<F>(self, default: F) -> &'a mut V
where F: FnOnce(&K) -> V,

Ensures a value is in the entry by inserting, if empty, the result of the default function. This method allows for generating key-derived values for insertion by providing the default function a reference to the key that was moved during the .entry(key) method call.

The reference to the moved key is provided so that cloning or copying the key is unnecessary, unlike with .or_insert_with(|| ... ).

§Examples
use std::collections::HashMap;

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

map.entry("poneyland").or_insert_with_key(|key| key.chars().count());

assert_eq!(map["poneyland"], 9);
1.10.0 · Source

pub fn key(&self) -> &K

Returns a reference to this entry’s key.

§Examples
use std::collections::HashMap;

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

pub fn and_modify<F>(self, f: F) -> Entry<'a, K, V>
where F: FnOnce(&mut V),

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

§Examples
use std::collections::HashMap;

let mut map: HashMap<&str, u32> = HashMap::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);
1.83.0 · Source

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

Sets the value of the entry, and returns an OccupiedEntry.

§Examples
use std::collections::HashMap;

let mut map: HashMap<&str, String> = HashMap::new();
let entry = map.entry("poneyland").insert_entry("hoho".to_string());

assert_eq!(entry.key(), &"poneyland");
Source§

impl<'a, K, V> Entry<'a, K, V>
where V: Default,

1.28.0 · Source

pub fn or_default(self) -> &'a mut V

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
use std::collections::HashMap;

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

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

Trait Implementations

1.12.0 · Source§

impl<K, V> Debug for Entry<'_, K, V>
where K: Debug, V: Debug,

Source§

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

Formats the value using the given formatter. Read more