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use std::borrow::Borrow;
use std::cell::{Cell, UnsafeCell};
use std::collections::HashMap;
use std::hash::Hash;
use stable_deref_trait::StableDeref;
pub struct FrozenMap<K, V> {
map: UnsafeCell<HashMap<K, V>>,
in_use: Cell<bool>,
}
impl<K: Eq + Hash, V: StableDeref> FrozenMap<K, V> {
pub fn new() -> Self {
Self {
map: UnsafeCell::new(Default::default()),
in_use: Cell::new(false)
}
}
pub fn insert(&self, k: K, v: V) -> &V::Target {
assert!(!self.in_use.get());
self.in_use.set(true);
let ret = unsafe {
let map = self.map.get();
&*(*map).entry(k).or_insert(v)
};
self.in_use.set(false);
ret
}
pub fn get<Q: ?Sized>(&self, k: &Q) -> Option<&V::Target>
where
K: Borrow<Q>,
Q: Hash + Eq,
{
assert!(!self.in_use.get());
self.in_use.set(true);
let ret = unsafe {
let map = self.map.get();
(*map).get(k).map(|x| &**x)
};
self.in_use.set(false);
ret
}
}
pub struct FrozenVec<T> {
vec: UnsafeCell<Vec<T>>,
}
impl<T: StableDeref> FrozenVec<T> {
pub fn new() -> Self {
Self {
vec: UnsafeCell::new(Default::default()),
}
}
pub fn push(&self, val: T) {
unsafe {
let vec = self.vec.get();
(*vec).push(val)
}
}
pub fn get(&self, index: usize) -> Option<&T::Target> {
unsafe {
let vec = self.vec.get();
(*vec).get(index).map(|x| &**x)
}
}
}