1.0.0[][src]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.

Methods

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

Important traits for &'_ mut I

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");Run

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);Run

Important traits for &'_ mut I

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);
}Run

Important traits for &'_ mut I

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);Run

Important traits for &'_ mut I

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);Run

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);Run

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);Run

🔬 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);
}
Run

🔬 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();
        }
    }
}Run

Trait Implementations

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

Formats the value using the given formatter. Read more

Auto Trait Implementations

impl<'a, K, V> !Send for OccupiedEntry<'a, K, V>

impl<'a, K, V> !Sync for OccupiedEntry<'a, K, V>

Blanket Implementations

impl<T, U> TryFrom for T where
    T: From<U>, 
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🔬 This is a nightly-only experimental API. (try_from #33417)

The type returned in the event of a conversion error.

🔬 This is a nightly-only experimental API. (try_from #33417)

Performs the conversion.

impl<T> From for T
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Performs the conversion.

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

🔬 This is a nightly-only experimental API. (try_from #33417)

The type returned in the event of a conversion error.

🔬 This is a nightly-only experimental API. (try_from #33417)

Performs the conversion.

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

Performs the conversion.

impl<T> Borrow for T where
    T: ?Sized
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Important traits for &'_ mut I

Immutably borrows from an owned value. Read more

impl<T> BorrowMut for T where
    T: ?Sized
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Important traits for &'_ mut I

Mutably borrows from an owned value. Read more

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

🔬 This is a nightly-only experimental API. (get_type_id #27745)

this method will likely be replaced by an associated static

Gets the TypeId of self. Read more