--- /dev/null
+pub use rustc_hash::FxHashMap;
+use std::borrow::Borrow;
+use std::collections::hash_map::Entry;
+use std::fmt;
+use std::hash::Hash;
+
+/// A deterministic wrapper around FxHashMap that does not provide iteration support.
+///
+/// It supports insert, remove, get and get_mut functions from FxHashMap.
+/// It also allows to convert hashmap to a sorted vector with the method `into_sorted_vector()`.
+#[derive(Clone)]
+pub struct StableMap<K, V> {
+ base: FxHashMap<K, V>,
+}
+
+impl<K, V> Default for StableMap<K, V>
+where
+ K: Eq + Hash,
+{
+ fn default() -> StableMap<K, V> {
+ StableMap::new()
+ }
+}
+
+impl<K, V> fmt::Debug for StableMap<K, V>
+where
+ K: Eq + Hash + fmt::Debug,
+ V: fmt::Debug,
+{
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ write!(f, "{:?}", self.base)
+ }
+}
+
+impl<K, V> PartialEq for StableMap<K, V>
+where
+ K: Eq + Hash,
+ V: PartialEq,
+{
+ fn eq(&self, other: &StableMap<K, V>) -> bool {
+ self.base == other.base
+ }
+}
+
+impl<K, V> Eq for StableMap<K, V>
+where
+ K: Eq + Hash,
+ V: Eq,
+{
+}
+
+impl<K, V> StableMap<K, V>
+where
+ K: Eq + Hash,
+{
+ pub fn new() -> StableMap<K, V> {
+ StableMap { base: FxHashMap::default() }
+ }
+
+ pub fn into_sorted_vector(self) -> Vec<(K, V)>
+ where
+ K: Ord + Copy,
+ {
+ let mut vector = self.base.into_iter().collect::<Vec<_>>();
+ vector.sort_unstable_by_key(|pair| pair.0);
+ vector
+ }
+
+ pub fn entry(&mut self, k: K) -> Entry<'_, K, V> {
+ self.base.entry(k)
+ }
+
+ pub fn get<Q: ?Sized>(&self, k: &Q) -> Option<&V>
+ where
+ K: Borrow<Q>,
+ Q: Hash + Eq,
+ {
+ self.base.get(k)
+ }
+
+ pub fn get_mut<Q: ?Sized>(&mut self, k: &Q) -> Option<&mut V>
+ where
+ K: Borrow<Q>,
+ Q: Hash + Eq,
+ {
+ self.base.get_mut(k)
+ }
+
+ pub fn insert(&mut self, k: K, v: V) -> Option<V> {
+ self.base.insert(k, v)
+ }
+
+ pub fn remove<Q: ?Sized>(&mut self, k: &Q) -> Option<V>
+ where
+ K: Borrow<Q>,
+ Q: Hash + Eq,
+ {
+ self.base.remove(k)
+ }
+}