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Struct std::collections::hash_map::OccupiedEntry

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

A view into an occupied entry in a HashMap. It is part of the Entry enum.

Implementations

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

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 R
impl<W: Write + ?Sized, '_> Write for &'_ mut W
[src]1.10.0

Gets a reference to the key in the entry.

Examples

use std::collections::HashMap;

let mut map: HashMap<&str, u32> = HashMap::new();
map.entry("poneyland").or_insert(12);
assert_eq!(map.entry("poneyland").key(), &"poneyland");

pub fn remove_entry(self) -> (K, V)[src]1.12.0

Take the ownership of the key and value from the map.

Examples

use std::collections::HashMap;
use std::collections::hash_map::Entry;

let mut map: HashMap<&str, u32> = HashMap::new();
map.entry("poneyland").or_insert(12);

if let Entry::Occupied(o) = map.entry("poneyland") {
    // We delete the entry from the map.
    o.remove_entry();
}

assert_eq!(map.contains_key("poneyland"), false);

pub fn get(&self) -> &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 R
impl<W: Write + ?Sized, '_> Write for &'_ mut W
[src]

Gets a reference to the value in the entry.

Examples

use std::collections::HashMap;
use std::collections::hash_map::Entry;

let mut map: HashMap<&str, u32> = HashMap::new();
map.entry("poneyland").or_insert(12);

if let Entry::Occupied(o) = map.entry("poneyland") {
    assert_eq!(o.get(), &12);
}

pub fn get_mut(&mut self) -> &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 R
impl<W: Write + ?Sized, '_> Write for &'_ mut W
[src]

Gets a mutable reference to the value in the entry.

If you need a reference to the OccupiedEntry which may outlive the destruction of the Entry value, see into_mut.

Examples

use std::collections::HashMap;
use std::collections::hash_map::Entry;

let mut map: HashMap<&str, u32> = HashMap::new();
map.entry("poneyland").or_insert(12);

assert_eq!(map["poneyland"], 12);
if let Entry::Occupied(mut o) = map.entry("poneyland") {
    *o.get_mut() += 10;
    assert_eq!(*o.get(), 22);

    // We can use the same Entry multiple times.
    *o.get_mut() += 2;
}

assert_eq!(map["poneyland"], 24);

pub fn into_mut(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 R
impl<W: Write + ?Sized, '_> Write for &'_ mut W
[src]

Converts the OccupiedEntry into a mutable reference to the value in the entry with a lifetime bound to the map itself.

If you need multiple references to the OccupiedEntry, see get_mut.

Examples

use std::collections::HashMap;
use std::collections::hash_map::Entry;

let mut map: HashMap<&str, u32> = HashMap::new();
map.entry("poneyland").or_insert(12);

assert_eq!(map["poneyland"], 12);
if let Entry::Occupied(o) = map.entry("poneyland") {
    *o.into_mut() += 10;
}

assert_eq!(map["poneyland"], 22);

pub fn insert(&mut self, value: V) -> V[src]

Sets the value of the entry, and returns the entry's old value.

Examples

use std::collections::HashMap;
use std::collections::hash_map::Entry;

let mut map: HashMap<&str, u32> = HashMap::new();
map.entry("poneyland").or_insert(12);

if let Entry::Occupied(mut o) = map.entry("poneyland") {
    assert_eq!(o.insert(15), 12);
}

assert_eq!(map["poneyland"], 15);

pub fn remove(self) -> V[src]

Takes the value out of the entry, and returns it.

Examples

use std::collections::HashMap;
use std::collections::hash_map::Entry;

let mut map: HashMap<&str, u32> = HashMap::new();
map.entry("poneyland").or_insert(12);

if let Entry::Occupied(o) = map.entry("poneyland") {
    assert_eq!(o.remove(), 12);
}

assert_eq!(map.contains_key("poneyland"), false);

pub fn replace_entry(self, value: V) -> (K, V)[src]

🔬 This is a nightly-only experimental API. (map_entry_replace #44286)

Replaces the entry, returning the old key and value. The new key in the hash map will be the key used to create this entry.

Examples

#![feature(map_entry_replace)]
use std::collections::hash_map::{Entry, HashMap};
use std::rc::Rc;

let mut map: HashMap<Rc<String>, u32> = HashMap::new();
map.insert(Rc::new("Stringthing".to_string()), 15);

let my_key = Rc::new("Stringthing".to_string());

if let Entry::Occupied(entry) = map.entry(my_key) {
    // Also replace the key with a handle to our other key.
    let (old_key, old_value): (Rc<String>, u32) = entry.replace_entry(16);
}

pub fn replace_key(self) -> K[src]

🔬 This is a nightly-only experimental API. (map_entry_replace #44286)

Replaces the key in the hash map with the key used to create this entry.

Examples

#![feature(map_entry_replace)]
use std::collections::hash_map::{Entry, HashMap};
use std::rc::Rc;

let mut map: HashMap<Rc<String>, u32> = HashMap::new();
let mut known_strings: Vec<Rc<String>> = Vec::new();

// Initialise known strings, run program, etc.

reclaim_memory(&mut map, &known_strings);

fn reclaim_memory(map: &mut HashMap<Rc<String>, u32>, known_strings: &[Rc<String>] ) {
    for s in known_strings {
        if let Entry::Occupied(entry) = map.entry(s.clone()) {
            // Replaces the entry's key with our version of it in `known_strings`.
            entry.replace_key();
        }
    }
}

Trait Implementations

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

Auto Trait Implementations

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

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

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

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

impl<'a, K, V> !UnwindSafe for OccupiedEntry<'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.

© 2010 The Rust Project Developers
Licensed under the Apache License, Version 2.0 or the MIT license, at your option.
https://doc.rust-lang.org/std/collections/hash_map/struct.OccupiedEntry.html