Struct OccupiedEntry

pub struct OccupiedEntry<'a, T, S> { /* private fields */ }

🔬This is a nightly-only experimental API. (hash_set_entry #60896)

Available on crate feature map only.

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

Examples

#![feature(hash_set_entry)]

use std::collections::hash_set::{Entry, HashSet};

let mut set = HashSet::new();
set.extend(["a", "b", "c"]);

let _entry_o = set.entry("a").insert();
assert_eq!(set.len(), 3);

// Existing key
match set.entry("a") {
    Entry::Vacant(_) => unreachable!(),
    Entry::Occupied(view) => {
        assert_eq!(view.get(), &"a");
    }
}

assert_eq!(set.len(), 3);

// Existing key (take)
match set.entry("c") {
    Entry::Vacant(_) => unreachable!(),
    Entry::Occupied(view) => {
        assert_eq!(view.remove(), "c");
    }
}
assert_eq!(set.get(&"c"), None);
assert_eq!(set.len(), 2);

Implementations

impl<T, S> OccupiedEntry<'_, T, S>

pub fn get(&self) -> &T

🔬This is a nightly-only experimental API. (hash_set_entry #60896)

Gets a reference to the value in the entry.

Examples

#![feature(hash_set_entry)]

use std::collections::hash_set::{Entry, HashSet};

let mut set = HashSet::new();
set.entry("poneyland").or_insert();

match set.entry("poneyland") {
    Entry::Vacant(_) => panic!(),
    Entry::Occupied(entry) => assert_eq!(entry.get(), &"poneyland"),
}

pub fn remove(self) -> T

🔬This is a nightly-only experimental API. (hash_set_entry #60896)

Takes the value out of the entry, and returns it. Keeps the allocated memory for reuse.

Examples

#![feature(hash_set_entry)]

use std::collections::HashSet;
use std::collections::hash_set::Entry;

let mut set = HashSet::new();
// The set is empty
assert!(set.is_empty() && set.capacity() == 0);

set.entry("poneyland").or_insert();
let capacity_before_remove = set.capacity();

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

assert_eq!(set.contains("poneyland"), false);
// Now set hold none elements but capacity is equal to the old one
assert!(set.len() == 0 && set.capacity() == capacity_before_remove);

Trait Implementations

impl<T, S> Debug for OccupiedEntry<'_, T, S>

where T: Debug,

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

Formats the value using the given formatter.

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