Struct VacantEntry

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

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

Available on crate feature std only.

A view into a vacant 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::<&str>::new();

let entry_v = match set.entry("a") {
    Entry::Vacant(view) => view,
    Entry::Occupied(_) => unreachable!(),
};
entry_v.insert();
assert!(set.contains("a") && set.len() == 1);

// Nonexistent key (insert)
match set.entry("b") {
    Entry::Vacant(view) => view.insert(),
    Entry::Occupied(_) => unreachable!(),
}
assert!(set.contains("b") && set.len() == 2);

Implementations

impl<'a, T, S> VacantEntry<'a, T, S>

pub fn get(&self) -> &T

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

Gets a reference to the value that would be used when inserting through the VacantEntry.

Examples

#![feature(hash_set_entry)]

use std::collections::HashSet;

let mut set = HashSet::new();
assert_eq!(set.entry("poneyland").get(), &"poneyland");

pub fn into_value(self) -> T

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

Take ownership of the value.

Examples

#![feature(hash_set_entry)]

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

let mut set = HashSet::new();

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

pub fn insert(self)

where T: Hash, S: BuildHasher,

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

Sets the value of the entry with the VacantEntry’s value.

Examples

#![feature(hash_set_entry)]

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

let mut set = HashSet::new();

if let Entry::Vacant(o) = set.entry("poneyland") {
    o.insert();
}
assert!(set.contains("poneyland"));

Trait Implementations

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

where T: Debug,

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

Formats the value using the given formatter.

Layout

Note: Unable to compute type layout, possibly due to this type having generic parameters. Layout can only be computed for concrete, fully-instantiated types.