pub struct RawEntryBuilderMut<'a, K, V, S, A: Allocator = Global> { /* private fields */ }
Expand description

A builder for computing where in a HashMap a key-value pair would be stored.

See the HashMap::raw_entry_mut docs for usage examples.

Examples

use hashbrown::hash_map::{RawEntryBuilderMut, RawEntryMut::Vacant, RawEntryMut::Occupied};
use hashbrown::HashMap;
use core::hash::{BuildHasher, Hash};

let mut map = HashMap::new();
map.extend([(1, 11), (2, 12), (3, 13), (4, 14), (5, 15), (6, 16)]);
assert_eq!(map.len(), 6);

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()
}

let builder: RawEntryBuilderMut<_, _, _> = map.raw_entry_mut();

// Existing key
match builder.from_key(&6) {
    Vacant(_) => unreachable!(),
    Occupied(view) => assert_eq!(view.get(), &16),
}

for key in 0..12 {
    let hash = compute_hash(map.hasher(), &key);
    let value = map.get(&key).cloned();
    let key_value = value.as_ref().map(|v| (&key, v));

    println!("Key: {} and value: {:?}", key, value);

    match map.raw_entry_mut().from_key(&key) {
        Occupied(mut o) => assert_eq!(Some(o.get_key_value()), key_value),
        Vacant(_) => assert_eq!(value, None),
    }
    match map.raw_entry_mut().from_key_hashed_nocheck(hash, &key) {
        Occupied(mut o) => assert_eq!(Some(o.get_key_value()), key_value),
        Vacant(_) => assert_eq!(value, None),
    }
    match map.raw_entry_mut().from_hash(hash, |q| *q == key) {
        Occupied(mut o) => assert_eq!(Some(o.get_key_value()), key_value),
        Vacant(_) => assert_eq!(value, None),
    }
}

assert_eq!(map.len(), 6);

Implementations§

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impl<'a, K, V, S, A: Allocator> RawEntryBuilderMut<'a, K, V, S, A>

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pub fn from_key<Q>(self, k: &Q) -> RawEntryMut<'a, K, V, S, A>where S: BuildHasher, Q: Hash + Equivalent<K> + ?Sized,

Creates a RawEntryMut from the given key.

Examples
use hashbrown::hash_map::{HashMap, RawEntryMut};

let mut map: HashMap<&str, u32> = HashMap::new();
let key = "a";
let entry: RawEntryMut<&str, u32, _> = map.raw_entry_mut().from_key(&key);
entry.insert(key, 100);
assert_eq!(map[&"a"], 100);
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pub fn from_key_hashed_nocheck<Q>( self, hash: u64, k: &Q ) -> RawEntryMut<'a, K, V, S, A>where Q: Equivalent<K> + ?Sized,

Creates a RawEntryMut from the given key and its hash.

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

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()
}

let mut map: HashMap<&str, u32> = HashMap::new();
let key = "a";
let hash = compute_hash(map.hasher(), &key);
let entry: RawEntryMut<&str, u32, _> = map.raw_entry_mut().from_key_hashed_nocheck(hash, &key);
entry.insert(key, 100);
assert_eq!(map[&"a"], 100);
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impl<'a, K, V, S, A: Allocator> RawEntryBuilderMut<'a, K, V, S, A>

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pub fn from_hash<F>(self, hash: u64, is_match: F) -> RawEntryMut<'a, K, V, S, A>where for<'b> F: FnMut(&'b K) -> bool,

Creates a RawEntryMut from the given hash and matching function.

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

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()
}

let mut map: HashMap<&str, u32> = HashMap::new();
let key = "a";
let hash = compute_hash(map.hasher(), &key);
let entry: RawEntryMut<&str, u32, _> = map.raw_entry_mut().from_hash(hash, |k| k == &key);
entry.insert(key, 100);
assert_eq!(map[&"a"], 100);

Trait Implementations§

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impl<K, V, S, A: Allocator> Debug for RawEntryBuilderMut<'_, 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§

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impl<'a, K, V, S, A> RefUnwindSafe for RawEntryBuilderMut<'a, K, V, S, A>where A: RefUnwindSafe, K: RefUnwindSafe, S: RefUnwindSafe, V: RefUnwindSafe,

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impl<'a, K, V, S, A> Send for RawEntryBuilderMut<'a, K, V, S, A>where A: Send, K: Send, S: Send, V: Send,

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

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

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impl<'a, K, V, S, A = Global> !UnwindSafe for RawEntryBuilderMut<'a, K, V, S, A>

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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.