pub struct VacantEntryRef<'a, 'b, K, Q: ?Sized, V, S, A: Allocator + Clone = Global> { /* private fields */ }
Expand description

A view into a vacant entry in a HashMap. It is part of the EntryRef enum.

Examples

use hashbrown::hash_map::{EntryRef, HashMap, VacantEntryRef};

let mut map = HashMap::<String, i32>::new();

let entry_v: VacantEntryRef<_, _, _, _> = match map.entry_ref("a") {
    EntryRef::Vacant(view) => view,
    EntryRef::Occupied(_) => unreachable!(),
};
entry_v.insert(10);
assert!(map["a"] == 10 && map.len() == 1);

// Nonexistent key (insert and update)
match map.entry_ref("b") {
    EntryRef::Occupied(_) => unreachable!(),
    EntryRef::Vacant(view) => {
        let value = view.insert(2);
        assert_eq!(*value, 2);
        *value = 20;
    }
}
assert!(map["b"] == 20 && map.len() == 2);

Implementations

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

Examples
use hashbrown::HashMap;

let mut map: HashMap<String, u32> = HashMap::new();
let key: &str = "poneyland";
assert_eq!(map.entry_ref(key).key(), "poneyland");

Take ownership of the key.

Examples
use hashbrown::hash_map::{EntryRef, HashMap};

let mut map: HashMap<String, u32> = HashMap::new();
let key: &str = "poneyland";

match map.entry_ref(key) {
    EntryRef::Occupied(_) => panic!(),
    EntryRef::Vacant(v) => assert_eq!(v.into_key(), "poneyland".to_owned()),
}

Sets the value of the entry with the VacantEntryRef’s key, and returns a mutable reference to it.

Examples
use hashbrown::HashMap;
use hashbrown::hash_map::EntryRef;

let mut map: HashMap<String, u32> = HashMap::new();
let key: &str = "poneyland";

if let EntryRef::Vacant(o) = map.entry_ref(key) {
    o.insert(37);
}
assert_eq!(map["poneyland"], 37);

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.