# Enum std::collections::hash_map::RawEntryMut

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    pub enum RawEntryMut<'a, K: 'a, V: 'a, S: 'a> {
        Occupied(RawOccupiedEntryMut<'a, K, V, S>),
        Vacant(RawVacantEntryMut<'a, K, V, S>),
    }

🔬This is a nightly-only experimental API. (`hash_raw_entry` #56167)
Expand description

A view into a single entry in a map, which may either be vacant or occupied.

This is a lower-level version of `Entry`.

This `enum` is constructed through the `raw_entry_mut` method on `HashMap`, then calling one of the methods of that `RawEntryBuilderMut`.

## Variants§

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### Occupied(RawOccupiedEntryMut<'a, K, V, S>)

🔬This is a nightly-only experimental API. (`hash_raw_entry` #56167)

An occupied entry.

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### Vacant(RawVacantEntryMut<'a, K, V, S>)

🔬This is a nightly-only experimental API. (`hash_raw_entry` #56167)

A vacant entry.

## Implementations§

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### impl<'a, K, V, S> RawEntryMut<'a, K, V, S>

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#### pub fn or_insert(self, default_key: K, default_val: V) -> (&'a mut K, &'a mut V)where K: Hash, S: BuildHasher,

🔬This is a nightly-only experimental API. (`hash_raw_entry` #56167)

Ensures a value is in the entry by inserting the default if empty, and returns mutable references to the key and value in the entry.

##### Examples

    #![feature(hash_raw_entry)]
    use std::collections::HashMap;

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

    map.raw_entry_mut().from_key("poneyland").or_insert("poneyland", 3);
    assert_eq!(map["poneyland"], 3);

    *map.raw_entry_mut().from_key("poneyland").or_insert("poneyland", 10).1 *= 2;
    assert_eq!(map["poneyland"], 6);

Run
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#### pub fn or_insert_with<F>(self, default: F) -> (&'a mut K, &'a mut V)where F: FnOnce() -> (K, V), K: Hash, S: BuildHasher,

🔬This is a nightly-only experimental API. (`hash_raw_entry` #56167)

Ensures a value is in the entry by inserting the result of the default function if empty, and returns mutable references to the key and value in the entry.

##### Examples

    #![feature(hash_raw_entry)]
    use std::collections::HashMap;

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

    map.raw_entry_mut().from_key("poneyland").or_insert_with(|| {
        ("poneyland", "hoho".to_string())
    });

    assert_eq!(map["poneyland"], "hoho".to_string());

Run
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#### pub fn and_modify<F>(self, f: F) -> Selfwhere F: FnOnce(&mut K, &mut V),

🔬This is a nightly-only experimental API. (`hash_raw_entry` #56167)

Provides in-place mutable access to an occupied entry before any potential inserts into the map.

##### Examples

    #![feature(hash_raw_entry)]
    use std::collections::HashMap;

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

    map.raw_entry_mut()
       .from_key("poneyland")
       .and_modify(|_k, v| { *v += 1 })
       .or_insert("poneyland", 42);
    assert_eq!(map["poneyland"], 42);

    map.raw_entry_mut()
       .from_key("poneyland")
       .and_modify(|_k, v| { *v += 1 })
       .or_insert("poneyland", 0);
    assert_eq!(map["poneyland"], 43);

Run

## Trait Implementations§

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### impl<K: Debug, V: Debug, S> Debug for RawEntryMut<'_, K, V, S>

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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, S> RefUnwindSafe for RawEntryMut<'a, K, V, S>where K: RefUnwindSafe, S: RefUnwindSafe, V: RefUnwindSafe,

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### impl<'a, K, V, S> Send for RawEntryMut<'a, K, V, S>where K: Send, S: Send + Sync, V: Send,

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### impl<'a, K, V, S> Sync for RawEntryMut<'a, K, V, S>where K: Sync, S: Sync, V: Sync,

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### impl<'a, K, V, S> Unpin for RawEntryMut<'a, K, V, S>

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### impl<'a, K, V, S> !UnwindSafe for RawEntryMut<'a, K, V, S>

## Blanket Implementations§

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### impl<T> Any for Twhere 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 Twhere 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 Twhere 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 Twhere 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 Twhere 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 Twhere 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.