std::collections::hash_map

Struct VacantEntry

1.0.0 · source
pub struct VacantEntry<'a, K: 'a, V: 'a> { /* private fields */ }
Expand description

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

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impl<'a, K: 'a, V: 'a> VacantEntry<'a, K, V>

1.10.0 · source

pub fn key(&self) -> &K

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

§Examples
use std::collections::HashMap;

let mut map: HashMap<&str, u32> = HashMap::new();
assert_eq!(map.entry("poneyland").key(), &"poneyland");
1.12.0 · source

pub fn into_key(self) -> K

Take ownership of the key.

§Examples
use std::collections::HashMap;
use std::collections::hash_map::Entry;

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

if let Entry::Vacant(v) = map.entry("poneyland") {
    v.into_key();
}
1.0.0 · source

pub fn insert(self, value: V) -> &'a mut V

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

§Examples
use std::collections::HashMap;
use std::collections::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);
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pub fn insert_entry(self, value: V) -> OccupiedEntry<'a, K, V>

🔬This is a nightly-only experimental API. (entry_insert #65225)

Sets the value of the entry with the VacantEntry’s key, and returns an OccupiedEntry.

§Examples
#![feature(entry_insert)]
use std::collections::HashMap;
use std::collections::hash_map::Entry;

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

if let Entry::Vacant(o) = map.entry("poneyland") {
    o.insert_entry(37);
}
assert_eq!(map["poneyland"], 37);

Trait Implementations§

1.12.0 · source§

impl<K: Debug, V> Debug for VacantEntry<'_, K, V>

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more

Auto Trait Implementations§

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impl<'a, K, V> Freeze for VacantEntry<'a, K, V>
where K: Freeze,

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impl<'a, K, V> RefUnwindSafe for VacantEntry<'a, K, V>

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impl<'a, K, V> Send for VacantEntry<'a, K, V>
where K: Send, V: Send,

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impl<'a, K, V> Sync for VacantEntry<'a, K, V>
where K: Sync, V: Sync,

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impl<'a, K, V> Unpin for VacantEntry<'a, K, V>
where K: Unpin,

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impl<'a, K, V> !UnwindSafe for VacantEntry<'a, K, V>

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

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

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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.