Struct hashbrown::hash_map::VacantEntryRef
source · [−]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
sourceimpl<'a, 'b, K, Q: ?Sized, V, S, A: Allocator + Clone> VacantEntryRef<'a, 'b, K, Q, V, S, A>
impl<'a, 'b, K, Q: ?Sized, V, S, A: Allocator + Clone> VacantEntryRef<'a, 'b, K, Q, V, S, A>
sourcepub fn key(&self) -> &Q where
K: Borrow<Q>,
pub fn key(&self) -> &Q where
K: Borrow<Q>,
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");
sourcepub fn into_key(self) -> K where
K: From<&'b Q>,
pub fn into_key(self) -> K where
K: From<&'b Q>,
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()),
}
sourcepub fn insert(self, value: V) -> &'a mut V where
K: Hash + From<&'b Q>,
S: BuildHasher,
pub fn insert(self, value: V) -> &'a mut V where
K: Hash + From<&'b Q>,
S: BuildHasher,
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
Auto Trait Implementations
impl<'a, 'b, K, Q: ?Sized, V, S, A> RefUnwindSafe for VacantEntryRef<'a, 'b, K, Q, V, S, A> where
A: RefUnwindSafe,
K: RefUnwindSafe,
Q: RefUnwindSafe,
S: RefUnwindSafe,
V: RefUnwindSafe,
impl<'a, 'b, K, Q: ?Sized, V, S, A> Send for VacantEntryRef<'a, 'b, K, Q, V, S, A> where
A: Send,
K: Send,
Q: Sync,
S: Send,
V: Send,
impl<'a, 'b, K, Q: ?Sized, V, S, A> Sync for VacantEntryRef<'a, 'b, K, Q, V, S, A> where
A: Sync,
K: Sync,
Q: Sync,
S: Sync,
V: Sync,
impl<'a, 'b, K, Q: ?Sized, V, S, A> Unpin for VacantEntryRef<'a, 'b, K, Q, V, S, A> where
K: Unpin,
impl<'a, 'b, K, Q, V, S, A = Global> !UnwindSafe for VacantEntryRef<'a, 'b, K, Q, V, S, A>
Blanket Implementations
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more