pub struct OccupiedEntry<'a, T, S, A: Allocator + Clone = Global> { /* private fields */ }
Expand description

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

Examples

use hashbrown::hash_set::{Entry, HashSet, OccupiedEntry};

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

let _entry_o: OccupiedEntry<_, _> = 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

Gets a reference to the value in the entry.

Examples
use hashbrown::hash_set::{Entry, HashSet};

let mut set: HashSet<&str> = HashSet::new();
set.entry("poneyland").or_insert();

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

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

Examples
use hashbrown::HashSet;
use hashbrown::hash_set::Entry;

let mut set: HashSet<&str> = 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);

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

Panics

Will panic if this OccupiedEntry was created through Entry::insert.

Examples
 use hashbrown::hash_set::{Entry, HashSet};
 use std::rc::Rc;

 let mut set: HashSet<Rc<String>> = HashSet::new();
 let key_one = Rc::new("Stringthing".to_string());
 let key_two = Rc::new("Stringthing".to_string());

 set.insert(key_one.clone());
 assert!(Rc::strong_count(&key_one) == 2 && Rc::strong_count(&key_two) == 1);

 match set.entry(key_two.clone()) {
     Entry::Occupied(entry) => {
         let old_key: Rc<String> = entry.replace();
         assert!(Rc::ptr_eq(&key_one, &old_key));
     }
     Entry::Vacant(_) => panic!(),
 }

 assert!(Rc::strong_count(&key_one) == 1 && Rc::strong_count(&key_two) == 2);
 assert!(set.contains(&"Stringthing".to_owned()));

Trait Implementations

Formats the value using the given formatter. Read more

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Returns the argument unchanged.

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.