1.0.0[][src]Enum std::collections::hash_map::Entry

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

Variants

Occupied(OccupiedEntry<'a, K, V>)

An occupied entry.

Vacant(VacantEntry<'a, K, V>)

A vacant entry.

Implementations

impl<'a, K, V> Entry<'a, K, V>[src]

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

Notable traits for &'_ mut I

impl<'_, I> Iterator for &'_ mut I where
    I: Iterator + ?Sized
type Item = <I as Iterator>::Item;impl<'_, F> Future for &'_ mut F where
    F: Unpin + Future + ?Sized
type Output = <F as Future>::Output;impl<R: Read + ?Sized> Read for &mut Rimpl<W: Write + ?Sized> Write for &mut W
[src]

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);
Run

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

Notable traits for &'_ mut I

impl<'_, I> Iterator for &'_ mut I where
    I: Iterator + ?Sized
type Item = <I as Iterator>::Item;impl<'_, F> Future for &'_ mut F where
    F: Unpin + Future + ?Sized
type Output = <F as Future>::Output;impl<R: Read + ?Sized> Read for &mut Rimpl<W: Write + ?Sized> Write for &mut W
[src]

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

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

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

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

Notable traits for &'_ mut I

impl<'_, I> Iterator for &'_ mut I where
    I: Iterator + ?Sized
type Item = <I as Iterator>::Item;impl<'_, F> Future for &'_ mut F where
    F: Unpin + Future + ?Sized
type Output = <F as Future>::Output;impl<R: Read + ?Sized> Read for &mut Rimpl<W: Write + ?Sized> Write for &mut W
1.50.0[src]

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);
Run

pub fn key(&self) -> &K

Notable traits for &'_ mut I

impl<'_, I> Iterator for &'_ mut I where
    I: Iterator + ?Sized
type Item = <I as Iterator>::Item;impl<'_, F> Future for &'_ mut F where
    F: Unpin + Future + ?Sized
type Output = <F as Future>::Output;impl<R: Read + ?Sized> Read for &mut Rimpl<W: Write + ?Sized> Write for &mut W
1.10.0[src]

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");
Run

pub fn and_modify<F>(self, f: F) -> Self where
    F: FnOnce(&mut V), 
1.26.0[src]

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);
Run

pub fn insert(self, value: V) -> OccupiedEntry<'a, K, V>[src]

🔬 This is a nightly-only experimental API. (entry_insert #65225)

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

Examples

#![feature(entry_insert)]
use std::collections::HashMap;

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

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

impl<'a, K, V: Default> Entry<'a, K, V>[src]

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

Notable traits for &'_ mut I

impl<'_, I> Iterator for &'_ mut I where
    I: Iterator + ?Sized
type Item = <I as Iterator>::Item;impl<'_, F> Future for &'_ mut F where
    F: Unpin + Future + ?Sized
type Output = <F as Future>::Output;impl<R: Read + ?Sized> Read for &mut Rimpl<W: Write + ?Sized> Write for &mut W
1.28.0[src]

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);
Run

Trait Implementations

impl<K: Debug, V: Debug> Debug for Entry<'_, K, V>1.12.0[src]

Auto Trait Implementations

impl<'a, K, V> RefUnwindSafe for Entry<'a, K, V> where
    K: RefUnwindSafe,
    V: RefUnwindSafe
[src]

impl<'a, K, V> Send for Entry<'a, K, V> where
    K: Send,
    V: Send
[src]

impl<'a, K, V> Sync for Entry<'a, K, V> where
    K: Sync,
    V: Sync
[src]

impl<'a, K, V> Unpin for Entry<'a, K, V> where
    K: Unpin
[src]

impl<'a, K, V> !UnwindSafe for Entry<'a, K, V>[src]

Blanket Implementations

impl<T> Any for T where
    T: 'static + ?Sized
[src]

impl<T> Borrow<T> for T where
    T: ?Sized
[src]

impl<T> BorrowMut<T> for T where
    T: ?Sized
[src]

impl<T> From<T> for T[src]

impl<T, U> Into<U> for T where
    U: From<T>, 
[src]

impl<T, U> TryFrom<U> for T where
    U: Into<T>, 
[src]

type Error = Infallible

The type returned in the event of a conversion error.

impl<T, U> TryInto<U> for T where
    U: TryFrom<T>, 
[src]

type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.