Struct OccupiedEntry

Source

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

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

Expand description

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§

Source §

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

Source

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"),
}

Source

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);