Struct hashbrown::hash_map::VacantEntry
source · pub struct VacantEntry<'a, K, V, S = DefaultHashBuilder, A: Allocator = Global> { /* private fields */ }
Expand description
A view into a vacant entry in a HashMap
.
It is part of the Entry
enum.
§Examples
use hashbrown::hash_map::{Entry, HashMap, VacantEntry};
let mut map = HashMap::<&str, i32>::new();
let entry_v: VacantEntry<_, _, _> = match map.entry("a") {
Entry::Vacant(view) => view,
Entry::Occupied(_) => unreachable!(),
};
entry_v.insert(10);
assert!(map[&"a"] == 10 && map.len() == 1);
// Nonexistent key (insert and update)
match map.entry("b") {
Entry::Occupied(_) => unreachable!(),
Entry::Vacant(view) => {
let value = view.insert(2);
assert_eq!(*value, 2);
*value = 20;
}
}
assert!(map[&"b"] == 20 && map.len() == 2);
Implementations§
source§impl<'a, K, V, S, A: Allocator> VacantEntry<'a, K, V, S, A>
impl<'a, K, V, S, A: Allocator> VacantEntry<'a, K, V, S, A>
sourcepub fn key(&self) -> &K
pub fn key(&self) -> &K
Gets a reference to the key that would be used when inserting a value
through the VacantEntry
.
§Examples
use hashbrown::HashMap;
let mut map: HashMap<&str, u32> = HashMap::new();
assert_eq!(map.entry("poneyland").key(), &"poneyland");
sourcepub fn into_key(self) -> K
pub fn into_key(self) -> K
Take ownership of the key.
§Examples
use hashbrown::hash_map::{Entry, HashMap};
let mut map: HashMap<&str, u32> = HashMap::new();
match map.entry("poneyland") {
Entry::Occupied(_) => panic!(),
Entry::Vacant(v) => assert_eq!(v.into_key(), "poneyland"),
}
sourcepub fn insert(self, value: V) -> &'a mut Vwhere
K: Hash,
S: BuildHasher,
pub fn insert(self, value: V) -> &'a mut Vwhere
K: Hash,
S: BuildHasher,
Sets the value of the entry with the VacantEntry
’s key,
and returns a mutable reference to it.
§Examples
use hashbrown::HashMap;
use hashbrown::hash_map::Entry;
let mut map: HashMap<&str, u32> = HashMap::new();
if let Entry::Vacant(o) = map.entry("poneyland") {
o.insert(37);
}
assert_eq!(map["poneyland"], 37);
sourcepub fn insert_entry(self, value: V) -> OccupiedEntry<'a, K, V, S, A>where
K: Hash,
S: BuildHasher,
pub fn insert_entry(self, value: V) -> OccupiedEntry<'a, K, V, S, A>where
K: Hash,
S: BuildHasher,
Sets the value of the entry with the VacantEntry
’s key,
and returns an OccupiedEntry
.
§Examples
use hashbrown::HashMap;
use hashbrown::hash_map::Entry;
let mut map: HashMap<&str, u32> = HashMap::new();
if let Entry::Vacant(v) = map.entry("poneyland") {
let o = v.insert_entry(37);
assert_eq!(o.get(), &37);
}
Trait Implementations§
Auto Trait Implementations§
impl<'a, K, V, S, A> Freeze for VacantEntry<'a, K, V, S, A>where
K: Freeze,
impl<'a, K, V, S, A> RefUnwindSafe for VacantEntry<'a, K, V, S, A>
impl<'a, K, V, S, A> Send for VacantEntry<'a, K, V, S, A>
impl<'a, K, V, S, A> Sync for VacantEntry<'a, K, V, S, A>
impl<'a, K, V, S, A> Unpin for VacantEntry<'a, K, V, S, A>where
K: Unpin,
impl<'a, K, V, S = DefaultHashBuilder, A = Global> !UnwindSafe for VacantEntry<'a, K, V, S, A>
Blanket Implementations§
source§impl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere
T: ?Sized,
source§fn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more