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use std::{borrow::Borrow, hash::Hash};
use dashmap::mapref::entry::Entry;
use turbo_tasks::FxDashMap;
/// A bidirectional [`FxDashMap`] that allows lookup by key or value.
///
/// As keys and values are stored twice, they should be small types, such as
/// [`Arc`][`std::sync::Arc`].
pub struct BiMap<K, V> {
forward: FxDashMap<K, V>,
reverse: FxDashMap<V, K>,
}
impl<K, V> BiMap<K, V>
where
K: Eq + Hash + Clone,
V: Eq + Hash + Clone,
{
pub fn new() -> Self {
Self {
forward: FxDashMap::default(),
reverse: FxDashMap::default(),
}
}
pub fn lookup_forward<Q>(&self, key: &Q) -> Option<V>
where
K: Borrow<Q>,
Q: Hash + Eq,
{
self.forward.get(key).map(|v| v.value().clone())
}
pub fn lookup_reverse<Q>(&self, key: &Q) -> Option<K>
where
V: Borrow<Q>,
Q: Hash + Eq,
{
self.reverse.get(key).map(|v| v.value().clone())
}
pub fn try_insert(&self, key: K, value: V) -> Result<(), V> {
match self.forward.entry(key) {
Entry::Occupied(e) => Err(e.get().clone()),
Entry::Vacant(e) => {
let e = e.insert_entry(value.clone());
let key = e.key().clone();
self.reverse.insert(value, key);
drop(e);
Ok(())
}
}
}
}
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