Struct hashbrown::hash_map::RawEntryBuilder
source · [−]pub struct RawEntryBuilder<'a, K, V, S, A: Allocator + Clone = 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
docs for usage examples.
Examples
use hashbrown::hash_map::{HashMap, RawEntryBuilder};
use core::hash::{BuildHasher, Hash};
let mut map = HashMap::new();
map.extend([(1, 10), (2, 20), (3, 30)]);
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()
}
for k in 0..6 {
let hash = compute_hash(map.hasher(), &k);
let v = map.get(&k).cloned();
let kv = v.as_ref().map(|v| (&k, v));
println!("Key: {} and value: {:?}", k, v);
let builder: RawEntryBuilder<_, _, _> = map.raw_entry();
assert_eq!(builder.from_key(&k), kv);
assert_eq!(map.raw_entry().from_hash(hash, |q| *q == k), kv);
assert_eq!(map.raw_entry().from_key_hashed_nocheck(hash, &k), kv);
}
Implementations
sourceimpl<'a, K, V, S, A: Allocator + Clone> RawEntryBuilder<'a, K, V, S, A>
impl<'a, K, V, S, A: Allocator + Clone> RawEntryBuilder<'a, K, V, S, A>
sourcepub fn from_key<Q: ?Sized>(self, k: &Q) -> Option<(&'a K, &'a V)> where
S: BuildHasher,
K: Borrow<Q>,
Q: Hash + Eq,
pub fn from_key<Q: ?Sized>(self, k: &Q) -> Option<(&'a K, &'a V)> where
S: BuildHasher,
K: Borrow<Q>,
Q: Hash + Eq,
Access an immutable entry by key.
Examples
use hashbrown::HashMap;
let map: HashMap<&str, u32> = [("a", 100), ("b", 200)].into();
let key = "a";
assert_eq!(map.raw_entry().from_key(&key), Some((&"a", &100)));
sourcepub fn from_key_hashed_nocheck<Q: ?Sized>(
self,
hash: u64,
k: &Q
) -> Option<(&'a K, &'a V)> where
K: Borrow<Q>,
Q: Eq,
pub fn from_key_hashed_nocheck<Q: ?Sized>(
self,
hash: u64,
k: &Q
) -> Option<(&'a K, &'a V)> where
K: Borrow<Q>,
Q: Eq,
Access an immutable entry by a key and its hash.
Examples
use core::hash::{BuildHasher, Hash};
use hashbrown::HashMap;
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 map: HashMap<&str, u32> = [("a", 100), ("b", 200)].into();
let key = "a";
let hash = compute_hash(map.hasher(), &key);
assert_eq!(map.raw_entry().from_key_hashed_nocheck(hash, &key), Some((&"a", &100)));
sourcepub fn from_hash<F>(self, hash: u64, is_match: F) -> Option<(&'a K, &'a V)> where
F: FnMut(&K) -> bool,
pub fn from_hash<F>(self, hash: u64, is_match: F) -> Option<(&'a K, &'a V)> where
F: FnMut(&K) -> bool,
Access an immutable entry by hash and matching function.
Examples
use core::hash::{BuildHasher, Hash};
use hashbrown::HashMap;
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 map: HashMap<&str, u32> = [("a", 100), ("b", 200)].into();
let key = "a";
let hash = compute_hash(map.hasher(), &key);
assert_eq!(map.raw_entry().from_hash(hash, |k| k == &key), Some((&"a", &100)));
Trait Implementations
Auto Trait Implementations
impl<'a, K, V, S, A> RefUnwindSafe for RawEntryBuilder<'a, K, V, S, A> where
A: RefUnwindSafe,
K: RefUnwindSafe,
S: RefUnwindSafe,
V: RefUnwindSafe,
impl<'a, K, V, S, A> Send for RawEntryBuilder<'a, K, V, S, A> where
A: Sync,
K: Sync,
S: Sync,
V: Sync,
impl<'a, K, V, S, A> Sync for RawEntryBuilder<'a, K, V, S, A> where
A: Sync,
K: Sync,
S: Sync,
V: Sync,
impl<'a, K, V, S, A> Unpin for RawEntryBuilder<'a, K, V, S, A>
impl<'a, K, V, S, A> UnwindSafe for RawEntryBuilder<'a, K, V, S, A> where
A: RefUnwindSafe,
K: RefUnwindSafe,
S: RefUnwindSafe,
V: RefUnwindSafe,
Blanket Implementations
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more