pub enum Entry<'a, K, V> where
K: 'a,
V: 'a, {
Occupied(OccupiedEntry<'a, K, V>),
Vacant(VacantEntry<'a, K, V>),
}
Expand description
Variants
Occupied(OccupiedEntry<'a, K, V>)
An occupied entry.
Vacant(VacantEntry<'a, K, V>)
A vacant entry.
Implementations
sourceimpl<'a, K, V> Entry<'a, K, V>
impl<'a, K, V> Entry<'a, K, V>
sourcepub fn or_insert(self, default: V) -> &'a mut V
pub fn or_insert(self, default: V) -> &'a mut V
Ensures a value is in the entry by inserting the default if empty, and returns a mutable reference to the value in the entry.
Examples
use std::collections::HashMap;
let mut map: HashMap<&str, u32> = HashMap::new();
map.entry("poneyland").or_insert(3);
assert_eq!(map["poneyland"], 3);
*map.entry("poneyland").or_insert(10) *= 2;
assert_eq!(map["poneyland"], 6);
sourcepub fn or_insert_with<F>(self, default: F) -> &'a mut V where
F: FnOnce() -> V,
pub fn or_insert_with<F>(self, default: F) -> &'a mut V where
F: FnOnce() -> V,
Ensures a value is in the entry by inserting the result of the default function if empty, and returns a mutable reference to the value in the entry.
Examples
use std::collections::HashMap;
let mut map: HashMap<&str, String> = HashMap::new();
let s = "hoho".to_string();
map.entry("poneyland").or_insert_with(|| s);
assert_eq!(map["poneyland"], "hoho".to_string());
1.50.0 · sourcepub fn or_insert_with_key<F>(self, default: F) -> &'a mut V where
F: FnOnce(&K) -> V,
pub fn or_insert_with_key<F>(self, default: F) -> &'a mut V where
F: FnOnce(&K) -> V,
Ensures a value is in the entry by inserting, if empty, the result of the default function.
This method allows for generating key-derived values for insertion by providing the default
function a reference to the key that was moved during the .entry(key)
method call.
The reference to the moved key is provided so that cloning or copying the key is
unnecessary, unlike with .or_insert_with(|| ... )
.
Examples
use std::collections::HashMap;
let mut map: HashMap<&str, usize> = HashMap::new();
map.entry("poneyland").or_insert_with_key(|key| key.chars().count());
assert_eq!(map["poneyland"], 9);
1.10.0 · sourcepub fn key(&self) -> &K
pub fn key(&self) -> &K
Returns a reference to this entry’s key.
Examples
use std::collections::HashMap;
let mut map: HashMap<&str, u32> = HashMap::new();
assert_eq!(map.entry("poneyland").key(), &"poneyland");
1.26.0 · sourcepub fn and_modify<F>(self, f: F) -> Entry<'a, K, V> where
F: FnOnce(&mut V),
pub fn and_modify<F>(self, f: F) -> Entry<'a, K, V> where
F: FnOnce(&mut V),
Provides in-place mutable access to an occupied entry before any potential inserts into the map.
Examples
use std::collections::HashMap;
let mut map: HashMap<&str, u32> = HashMap::new();
map.entry("poneyland")
.and_modify(|e| { *e += 1 })
.or_insert(42);
assert_eq!(map["poneyland"], 42);
map.entry("poneyland")
.and_modify(|e| { *e += 1 })
.or_insert(42);
assert_eq!(map["poneyland"], 43);
sourcepub fn insert_entry(self, value: V) -> OccupiedEntry<'a, K, V>
🔬 This is a nightly-only experimental API. (entry_insert
)
pub fn insert_entry(self, value: V) -> OccupiedEntry<'a, K, V>
entry_insert
)Sets the value of the entry, and returns an OccupiedEntry
.
Examples
#![feature(entry_insert)]
use std::collections::HashMap;
let mut map: HashMap<&str, String> = HashMap::new();
let entry = map.entry("poneyland").insert_entry("hoho".to_string());
assert_eq!(entry.key(), &"poneyland");
sourceimpl<'a, K, V> Entry<'a, K, V> where
V: Default,
impl<'a, K, V> Entry<'a, K, V> where
V: Default,
1.28.0 · sourcepub fn or_default(self) -> &'a mut V
pub fn or_default(self) -> &'a mut V
Ensures a value is in the entry by inserting the default value if empty, and returns a mutable reference to the value in the entry.
Examples
use std::collections::HashMap;
let mut map: HashMap<&str, Option<u32>> = HashMap::new();
map.entry("poneyland").or_default();
assert_eq!(map["poneyland"], None);
Trait Implementations
Auto Trait Implementations
impl<'a, K, V> RefUnwindSafe for Entry<'a, K, V> where
K: RefUnwindSafe,
V: RefUnwindSafe,
impl<'a, K, V> Send for Entry<'a, K, V> where
K: Send,
V: Send,
impl<'a, K, V> Sync for Entry<'a, K, V> where
K: Sync,
V: Sync,
impl<'a, K, V> Unpin for Entry<'a, K, V> where
K: Unpin,
impl<'a, K, V> !UnwindSafe for Entry<'a, K, V>
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
sourceimpl<T> Downcast for T where
T: Any,
impl<T> Downcast for T where
T: Any,
sourcefn into_any(self: Box<T, Global>) -> Box<dyn Any + 'static, Global>
fn into_any(self: Box<T, Global>) -> Box<dyn Any + 'static, Global>
Convert Box<dyn Trait>
(where Trait: Downcast
) to Box<dyn Any>
. Box<dyn Any>
can
then be further downcast
into Box<ConcreteType>
where ConcreteType
implements Trait
. Read more
sourcefn into_any_rc(self: Rc<T>) -> Rc<dyn Any + 'static>
fn into_any_rc(self: Rc<T>) -> Rc<dyn Any + 'static>
Convert Rc<Trait>
(where Trait: Downcast
) to Rc<Any>
. Rc<Any>
can then be
further downcast
into Rc<ConcreteType>
where ConcreteType
implements Trait
. Read more
sourcefn as_any(&self) -> &(dyn Any + 'static)
fn as_any(&self) -> &(dyn Any + 'static)
Convert &Trait
(where Trait: Downcast
) to &Any
. This is needed since Rust cannot
generate &Any
’s vtable from &Trait
’s. Read more
sourcefn as_any_mut(&mut self) -> &mut (dyn Any + 'static)
fn as_any_mut(&mut self) -> &mut (dyn Any + 'static)
Convert &mut Trait
(where Trait: Downcast
) to &Any
. This is needed since Rust cannot
generate &mut Any
’s vtable from &mut Trait
’s. Read more
sourceimpl<T> DowncastSync for T where
T: Any + Send + Sync,
impl<T> DowncastSync for T where
T: Any + Send + Sync,
sourceimpl<SS, SP> SupersetOf<SS> for SP where
SS: SubsetOf<SP>,
impl<SS, SP> SupersetOf<SS> for SP where
SS: SubsetOf<SP>,
sourcefn to_subset(&self) -> Option<SS>
fn to_subset(&self) -> Option<SS>
The inverse inclusion map: attempts to construct self
from the equivalent element of its
superset. Read more
sourcefn is_in_subset(&self) -> bool
fn is_in_subset(&self) -> bool
Checks if self
is actually part of its subset T
(and can be converted to it).
sourcefn to_subset_unchecked(&self) -> SS
fn to_subset_unchecked(&self) -> SS
Use with care! Same as self.to_subset
but without any property checks. Always succeeds.
sourcefn from_subset(element: &SS) -> SP
fn from_subset(element: &SS) -> SP
The inclusion map: converts self
to the equivalent element of its superset.