# Struct hashbrown::hash_set::VacantEntry

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    pub struct VacantEntry<'a, T, S, A: Allocator + Clone = Global> { /* private fields */ }

Expand description

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

## Examples

    use hashbrown::hash_set::{Entry, HashSet, VacantEntry};

    let mut set = HashSet::<&str>::new();

    let entry_v: VacantEntry<_, _> = match set.entry("a") {
        Entry::Vacant(view) => view,
        Entry::Occupied(_) => unreachable!(),
    };
    entry_v.insert();
    assert!(set.contains("a") && set.len() == 1);

    // Nonexistent key (insert)
    match set.entry("b") {
        Entry::Vacant(view) => view.insert(),
        Entry::Occupied(_) => unreachable!(),
    }
    assert!(set.contains("b") && set.len() == 2);

## Implementations

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### impl<'a, T, S, A: Allocator + Clone> VacantEntry<'a, T, S, A>

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#### pub fn get(&self) -> &T

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

##### Examples

    use hashbrown::HashSet;

    let mut set: HashSet<&str> = HashSet::new();
    assert_eq!(set.entry("poneyland").get(), &"poneyland");

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#### pub fn into_value(self) -> T

Take ownership of the value.

##### Examples

    use hashbrown::hash_set::{Entry, HashSet};

    let mut set: HashSet<&str> = HashSet::new();

    match set.entry("poneyland") {
        Entry::Occupied(_) => panic!(),
        Entry::Vacant(v) => assert_eq!(v.into_value(), "poneyland"),
    }

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#### pub fn insert(self) where
T: Hash,
S: BuildHasher,

Sets the value of the entry with the VacantEntry’s value.

##### Examples

    use hashbrown::HashSet;
    use hashbrown::hash_set::Entry;

    let mut set: HashSet<&str> = HashSet::new();

    if let Entry::Vacant(o) = set.entry("poneyland") {
        o.insert();
    }
    assert!(set.contains("poneyland"));

## Trait Implementations

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### impl<T: Debug, S, A: Allocator + Clone> Debug for VacantEntry<'_, T, S, A>

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

Formats the value using the given formatter. Read more

## Auto Trait Implementations

### impl<'a, T, S, A> RefUnwindSafe for VacantEntry<'a, T, S, A> where
A: RefUnwindSafe,
S: RefUnwindSafe,
T: RefUnwindSafe,

### impl<'a, T, S, A> Send for VacantEntry<'a, T, S, A> where
A: Send,
S: Send,
T: Send,

### impl<'a, T, S, A> Sync for VacantEntry<'a, T, S, A> where
A: Sync,
S: Sync,
T: Sync,

### impl<'a, T, S, A> Unpin for VacantEntry<'a, T, S, A> where
T: Unpin,

### impl<'a, T, S, A = Global> !UnwindSafe for VacantEntry<'a, T, S, A>

## 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,

const: unstable · source

#### 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,

const: unstable · source

#### 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

const: unstable · source

#### fn from(t: T) -> T

Returns the argument unchanged.

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

const: unstable · source

#### 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>,

#### type Error = Infallible

The type returned in the event of a conversion error.

const: unstable · source

#### 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>,

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

The type returned in the event of a conversion error.

const: unstable · source

#### fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.