# Enum hashbrown::hash_map::RawEntryMut

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    pub enum RawEntryMut<'a, K, V, S, A: Allocator + Clone = Global> {
        Occupied(RawOccupiedEntryMut<'a, K, V, S, A>),
        Vacant(RawVacantEntryMut<'a, K, V, S, A>),
    }

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`.

## Examples

    use core::hash::{BuildHasher, Hash};
    use hashbrown::hash_map::{HashMap, RawEntryMut, RawOccupiedEntryMut};

    let mut map = HashMap::new();
    map.extend([('a', 1), ('b', 2), ('c', 3)]);
    assert_eq!(map.len(), 3);

    fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
        use core::hash::Hasher;
        let mut state = hash_builder.build_hasher();
        key.hash(&mut state);
        state.finish()
    }

    // Existing key (insert)
    let raw: RawEntryMut<_, _, _> = map.raw_entry_mut().from_key(&'a');
    let _raw_o: RawOccupiedEntryMut<_, _, _> = raw.insert('a', 10);
    assert_eq!(map.len(), 3);

    // Nonexistent key (insert)
    map.raw_entry_mut().from_key(&'d').insert('d', 40);
    assert_eq!(map.len(), 4);

    // Existing key (or_insert)
    let hash = compute_hash(map.hasher(), &'b');
    let kv = map
        .raw_entry_mut()
        .from_key_hashed_nocheck(hash, &'b')
        .or_insert('b', 20);
    assert_eq!(kv, (&mut 'b', &mut 2));
    *kv.1 = 20;
    assert_eq!(map.len(), 4);

    // Nonexistent key (or_insert)
    let hash = compute_hash(map.hasher(), &'e');
    let kv = map
        .raw_entry_mut()
        .from_key_hashed_nocheck(hash, &'e')
        .or_insert('e', 50);
    assert_eq!(kv, (&mut 'e', &mut 50));
    assert_eq!(map.len(), 5);

    // Existing key (or_insert_with)
    let hash = compute_hash(map.hasher(), &'c');
    let kv = map
        .raw_entry_mut()
        .from_hash(hash, |q| q == &'c')
        .or_insert_with(|| ('c', 30));
    assert_eq!(kv, (&mut 'c', &mut 3));
    *kv.1 = 30;
    assert_eq!(map.len(), 5);

    // Nonexistent key (or_insert_with)
    let hash = compute_hash(map.hasher(), &'f');
    let kv = map
        .raw_entry_mut()
        .from_hash(hash, |q| q == &'f')
        .or_insert_with(|| ('f', 60));
    assert_eq!(kv, (&mut 'f', &mut 60));
    assert_eq!(map.len(), 6);

    println!("Our HashMap: {:?}", map);

    let mut vec: Vec<_> = map.iter().map(|(&k, &v)| (k, v)).collect();
    // The `Iter` iterator produces items in arbitrary order, so the
    // items must be sorted to test them against a sorted array.
    vec.sort_unstable();
    assert_eq!(vec, [('a', 10), ('b', 20), ('c', 30), ('d', 40), ('e', 50), ('f', 60)]);

## Variants

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

An occupied entry.

#### Examples

    use hashbrown::{hash_map::RawEntryMut, HashMap};
    let mut map: HashMap<_, _> = [("a", 100), ("b", 200)].into();

    match map.raw_entry_mut().from_key(&"a") {
        RawEntryMut::Vacant(_) => unreachable!(),
        RawEntryMut::Occupied(_) => { }
    }

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

A vacant entry.

#### Examples

    use hashbrown::{hash_map::RawEntryMut, HashMap};
    let mut map: HashMap<&str, i32> = HashMap::new();

    match map.raw_entry_mut().from_key("a") {
        RawEntryMut::Occupied(_) => unreachable!(),
        RawEntryMut::Vacant(_) => { }
    }

## Implementations

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### impl<'a, K, V, S, A: Allocator + Clone> RawEntryMut<'a, K, V, S, A>

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#### pub fn insert(self, key: K, value: V) -> RawOccupiedEntryMut<'a, K, V, S, A> where
K: Hash,
S: BuildHasher,

Sets the value of the entry, and returns a RawOccupiedEntryMut.

##### Examples

    use hashbrown::HashMap;

    let mut map: HashMap<&str, u32> = HashMap::new();
    let entry = map.raw_entry_mut().from_key("horseyland").insert("horseyland", 37);

    assert_eq!(entry.remove_entry(), ("horseyland", 37));

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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,

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

    use hashbrown::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);

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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,

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

    use hashbrown::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());

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

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

##### Examples

    use hashbrown::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);

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#### pub fn and_replace_entry_with<F>(self, f: F) -> Self where
F: FnOnce(&K, V) -> Option<V>,

Provides shared access to the key and owned access to the value of an occupied entry and allows to replace or remove it based on the value of the returned option.

##### Examples

    use hashbrown::HashMap;
    use hashbrown::hash_map::RawEntryMut;

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

    let entry = map
        .raw_entry_mut()
        .from_key("poneyland")
        .and_replace_entry_with(|_k, _v| panic!());

    match entry {
        RawEntryMut::Vacant(_) => {},
        RawEntryMut::Occupied(_) => panic!(),
    }

    map.insert("poneyland", 42);

    let entry = map
        .raw_entry_mut()
        .from_key("poneyland")
        .and_replace_entry_with(|k, v| {
            assert_eq!(k, &"poneyland");
            assert_eq!(v, 42);
            Some(v + 1)
        });

    match entry {
        RawEntryMut::Occupied(e) => {
            assert_eq!(e.key(), &"poneyland");
            assert_eq!(e.get(), &43);
        },
        RawEntryMut::Vacant(_) => panic!(),
    }

    assert_eq!(map["poneyland"], 43);

    let entry = map
        .raw_entry_mut()
        .from_key("poneyland")
        .and_replace_entry_with(|_k, _v| None);

    match entry {
        RawEntryMut::Vacant(_) => {},
        RawEntryMut::Occupied(_) => panic!(),
    }

    assert!(!map.contains_key("poneyland"));

## Trait Implementations

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### impl<K: Debug, V: Debug, S, A: Allocator + Clone> Debug for RawEntryMut<'_, K, V, 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, K, V, S, A> RefUnwindSafe for RawEntryMut<'a, K, V, S, A> where
A: RefUnwindSafe,
K: RefUnwindSafe,
S: RefUnwindSafe,
V: RefUnwindSafe,

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

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

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

### impl<'a, K, V, S, A = Global> !UnwindSafe for RawEntryMut<'a, K, V, 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.