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Bypass some duplicated work if you use the entry API

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This commit is contained in:
Gwilym Inzani 2023-05-23 21:10:27 +01:00
parent 1bb70aa24b
commit d393ad7e99
1 changed files with 16 additions and 22 deletions
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38
agb-hashmap/src/lib.rs
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@ -338,23 +338,8 @@ where
} }
} }
fn insert_and_get(&mut self, key: K, value: V) -> &'_ mut V { unsafe fn insert_new_and_get(&mut self, key: K, value: V, hash: HashType) -> &'_ mut V {
let hash = self.hash(&key); let location = self.nodes.insert_new(key, value, hash);
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)
};
// SAFETY: location is always valid // SAFETY: location is always valid
unsafe { unsafe {
@ -599,7 +584,7 @@ impl<K, V, ALLOCATOR: ClonableAllocator> IntoIterator for HashMap<K, V, ALLOCATO
mod entries { mod entries {
use core::{alloc::Allocator, hash::Hash}; 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. /// 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> { 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> { pub struct VacantEntry<'a, K: 'a, V: 'a, ALLOCATOR: Allocator> {
key: K, key: K,
map: &'a mut HashMap<K, V, ALLOCATOR>, map: &'a mut HashMap<K, V, ALLOCATOR>,
hash: HashType,
} }
impl<'a, K: 'a, V: 'a, ALLOCATOR: ClonableAllocator> VacantEntry<'a, K, V, ALLOCATOR> { 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 { pub(crate) unsafe fn new(
Self { key, map } 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` /// Gets a reference to the key that would be used when inserting a value through `VacantEntry`
@ -717,7 +707,8 @@ mod entries {
where where
K: Hash + Eq, 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) }, unsafe { OccupiedEntry::new(key, self, location) },
) )
} else { } 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) },
)
} }
} }
} }