Bypass some duplicated work if you use the entry API

This commit is contained in:
Gwilym Inzani 2023-05-23 21:10:27 +01:00
parent 1bb70aa24b
commit d393ad7e99

View file

@ -338,23 +338,8 @@ where
}
}
fn insert_and_get(&mut self, key: K, value: V) -> &'_ mut V {
let hash = self.hash(&key);
let location = if let Some(location) = self.nodes.location(&key, hash) {
// SAFETY: location is valid due to the above
unsafe {
self.nodes
.replace_at_location_unchecked(location, key, value);
}
location
} else {
if self.nodes.capacity() <= self.len() {
self.resize(self.nodes.backing_vec_size() * 2);
}
self.nodes.insert_new(key, value, hash)
};
unsafe fn insert_new_and_get(&mut self, key: K, value: V, hash: HashType) -> &'_ mut V {
let location = self.nodes.insert_new(key, value, hash);
// SAFETY: location is always valid
unsafe {
@ -599,7 +584,7 @@ impl<K, V, ALLOCATOR: ClonableAllocator> IntoIterator for HashMap<K, V, ALLOCATO
mod entries {
use core::{alloc::Allocator, hash::Hash};
use super::{ClonableAllocator, HashMap};
use super::{ClonableAllocator, HashMap, HashType};
/// A view into an occupied entry in a `HashMap`. This is part of the [`crate::Entry`] enum.
pub struct OccupiedEntry<'a, K: 'a, V: 'a, ALLOCATOR: Allocator> {
@ -695,11 +680,16 @@ mod entries {
pub struct VacantEntry<'a, K: 'a, V: 'a, ALLOCATOR: Allocator> {
key: K,
map: &'a mut HashMap<K, V, ALLOCATOR>,
hash: HashType,
}
impl<'a, K: 'a, V: 'a, ALLOCATOR: ClonableAllocator> VacantEntry<'a, K, V, ALLOCATOR> {
pub(crate) fn new(key: K, map: &'a mut HashMap<K, V, ALLOCATOR>) -> Self {
Self { key, map }
pub(crate) unsafe fn new(
key: K,
hash: HashType,
map: &'a mut HashMap<K, V, ALLOCATOR>,
) -> Self {
Self { key, map, hash }
}
/// Gets a reference to the key that would be used when inserting a value through `VacantEntry`
@ -717,7 +707,8 @@ mod entries {
where
K: Hash + Eq,
{
self.map.insert_and_get(self.key, value)
// SAFETY: by construction, this doesn't already exist in the hashmap and we were given the hash and key
unsafe { self.map.insert_new_and_get(self.key, value, self.hash) }
}
}
}
@ -832,7 +823,10 @@ where
unsafe { OccupiedEntry::new(key, self, location) },
)
} else {
Entry::Vacant(VacantEntry::new(key, self))
Entry::Vacant(
// SAFETY: item doesn't exist yet and the hash is correct here
unsafe { VacantEntry::new(key, hash, self) },
)
}
}
}