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use crate::reference::*;
use crate::table::Table;
pub struct TableHashmapFallbackWeak<
D: std::hash::Hash + std::cmp::Eq + std::fmt::Debug,
R: Reference<D>,
RW: ReferenceWeak<D, R>,
T: Table<D, R> + Default,
> {
m: std::collections::HashMap<u64, RW>,
fallback: T,
phantom_d: std::marker::PhantomData<D>,
phantom_r: std::marker::PhantomData<R>,
}
impl<D, R, RW, T> Default for TableHashmapFallbackWeak<D, R, RW, T>
where
D: std::hash::Hash + std::cmp::Eq + std::fmt::Debug,
R: Reference<D>,
RW: ReferenceWeak<D, R>,
T: Table<D, R> + Default,
{
fn default() -> Self {
Self {
m: std::collections::HashMap::default(),
fallback: T::default(),
phantom_d: std::marker::PhantomData,
phantom_r: std::marker::PhantomData,
}
}
}
impl<D, R, RW, T> Table<D, R> for TableHashmapFallbackWeak<D, R, RW, T>
where
D: std::hash::Hash + std::cmp::Eq + std::fmt::Debug,
R: Reference<D>,
RW: ReferenceWeak<D, R>,
T: Table<D, R> + Default,
{
fn get(&self, hash: u64, data: &D) -> Option<R> {
if let Some((_k, v)) = self.m.get_key_value(&hash) {
if let Some(up) = RW::weak_upgrade(v) {
if *R::strong_deref(&up) == *data {
return Some(up);
}
}
}
self.fallback.get(hash, &data)
}
fn get_or_insert<CF>(&mut self, hash: u64, mut data: D, creation_meta: CF) -> R
where
CF: FnOnce(&mut D),
{
use std::collections::hash_map::Entry;
let mut has_vacancy = false;
match self.m.entry(hash) {
Entry::Vacant(_ev) => {
has_vacancy = true;
}
Entry::Occupied(eo) => {
if let Some(up) = RW::weak_upgrade(eo.get()) {
if *R::strong_deref(&up) == data {
return up;
}
} else {
has_vacancy = true;
}
}
}
if has_vacancy {
let fallback_obj = self.fallback.get(hash, &data);
if let Some(fobj) = fallback_obj {
return fobj;
}
creation_meta(&mut data);
let obj = R::new(data);
let weak = RW::weak_downgrade(&obj);
let entry = self.m.entry(hash);
match entry {
Entry::Vacant(ev) => {
ev.insert(weak);
}
Entry::Occupied(mut eo) => {
assert!(RW::weak_upgrade(eo.get()).is_none());
*eo.get_mut() = weak;
}
}
obj
} else {
self.fallback.get_or_insert(hash, data, creation_meta)
}
}
}