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

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

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

A vacant entry.

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

An occupied entry.

Implementations

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

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

Notable traits for &'_ mut F

impl<'_, F> Future for &'_ mut F where
    F: Unpin + Future + ?Sized
type Output = <F as Future>::Output;impl<'_, I> Iterator for &'_ mut I where
    I: Iterator + ?Sized
type Item = <I as Iterator>::Item;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::BTreeMap;

let mut map: BTreeMap<&str, usize> = BTreeMap::new();
map.entry("poneyland").or_insert(12);

assert_eq!(map["poneyland"], 12);
Run

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

Notable traits for &'_ mut F

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

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

Notable traits for &'_ mut F

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

🔬 This is a nightly-only experimental API. (or_insert_with_key #71024)

Ensures a value is in the entry by inserting, if empty, the result of the default function, which takes the key as its argument, and returns a mutable reference to the value in the entry.

Examples

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

let mut map: BTreeMap<&str, usize> = BTreeMap::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 F

impl<'_, F> Future for &'_ mut F where
    F: Unpin + Future + ?Sized
type Output = <F as Future>::Output;impl<'_, I> Iterator for &'_ mut I where
    I: Iterator + ?Sized
type Item = <I as Iterator>::Item;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::BTreeMap;

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

pub fn and_modify<F>(self, f: F) -> Entry<'a, K, V> 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::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
[src]

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

Notable traits for &'_ mut F

impl<'_, F> Future for &'_ mut F where
    F: Unpin + Future + ?Sized
type Output = <F as Future>::Output;impl<'_, I> Iterator for &'_ mut I where
    I: Iterator + ?Sized
type Item = <I as Iterator>::Item;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::BTreeMap;

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

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

Trait Implementations

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

Auto Trait Implementations

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

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

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

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

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

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.