agb/agb-hashmap/src/node.rs

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2023-05-10 05:43:23 +10:00
use core::{
mem::{self, MaybeUninit},
ptr,
};
use crate::HashType;
pub(crate) struct Node<K, V> {
hash: HashType,
// distance_to_initial_bucket = -1 => key and value are uninit.
// distance_to_initial_bucket >= 0 => key and value are init
distance_to_initial_bucket: i32,
key: MaybeUninit<K>,
value: MaybeUninit<V>,
}
impl<K, V> Node<K, V> {
fn new() -> Self {
Self {
hash: 0,
distance_to_initial_bucket: -1,
key: MaybeUninit::uninit(),
value: MaybeUninit::uninit(),
}
}
pub(crate) fn new_with(key: K, value: V, hash: HashType) -> Self {
Self {
hash,
distance_to_initial_bucket: 0,
key: MaybeUninit::new(key),
value: MaybeUninit::new(value),
}
}
pub(crate) fn value_ref(&self) -> Option<&V> {
if self.has_value() {
Some(unsafe { self.value.assume_init_ref() })
} else {
None
}
}
pub(crate) fn value_mut(&mut self) -> Option<&mut V> {
if self.has_value() {
Some(unsafe { self.value.assume_init_mut() })
} else {
None
}
}
pub(crate) fn key_ref(&self) -> Option<&K> {
if self.distance_to_initial_bucket >= 0 {
Some(unsafe { self.key.assume_init_ref() })
} else {
None
}
}
pub(crate) fn key_value_ref(&self) -> Option<(&K, &V)> {
if self.has_value() {
Some(unsafe { (self.key.assume_init_ref(), self.value.assume_init_ref()) })
} else {
None
}
}
pub(crate) fn key_value_mut(&mut self) -> Option<(&K, &mut V)> {
if self.has_value() {
Some(unsafe { (self.key.assume_init_ref(), self.value.assume_init_mut()) })
} else {
None
}
}
pub(crate) fn has_value(&self) -> bool {
self.distance_to_initial_bucket >= 0
}
pub(crate) fn take_key_value(&mut self) -> Option<(K, V, HashType)> {
if self.has_value() {
let key = mem::replace(&mut self.key, MaybeUninit::uninit());
let value = mem::replace(&mut self.value, MaybeUninit::uninit());
self.distance_to_initial_bucket = -1;
Some(unsafe { (key.assume_init(), value.assume_init(), self.hash) })
} else {
None
}
}
pub(crate) fn replace_value(&mut self, value: V) -> V {
if self.has_value() {
let old_value = mem::replace(&mut self.value, MaybeUninit::new(value));
unsafe { old_value.assume_init() }
} else {
panic!("Cannot replace an uninitialised node");
}
}
pub(crate) fn replace(&mut self, key: K, value: V) -> (K, V) {
if self.has_value() {
let old_key = mem::replace(&mut self.key, MaybeUninit::new(key));
let old_value = mem::replace(&mut self.value, MaybeUninit::new(value));
unsafe { (old_key.assume_init(), old_value.assume_init()) }
} else {
panic!("Cannot replace an uninitialised node");
}
}
pub(crate) fn increment_distance(&mut self) {
self.distance_to_initial_bucket += 1;
}
pub(crate) fn decrement_distance(&mut self) {
self.distance_to_initial_bucket -= 1;
if self.distance_to_initial_bucket < 0 {
panic!("Cannot decrement distance to below 0");
}
}
pub(crate) fn distance(&self) -> i32 {
self.distance_to_initial_bucket
}
pub(crate) fn hash(&self) -> HashType {
self.hash
}
}
impl<K, V> Drop for Node<K, V> {
fn drop(&mut self) {
if self.has_value() {
unsafe { ptr::drop_in_place(self.key.as_mut_ptr()) };
unsafe { ptr::drop_in_place(self.value.as_mut_ptr()) };
}
}
}
impl<K, V> Default for Node<K, V> {
fn default() -> Self {
Self::new()
}
}