--- /dev/null
+pub use rustc_hash::FxHashSet;
+use std::borrow::Borrow;
+use std::fmt;
+use std::hash::Hash;
+
+/// A deterministic wrapper around FxHashSet that does not provide iteration support.
+///
+/// It supports insert, remove, get functions from FxHashSet.
+/// It also allows to convert hashset to a sorted vector with the method `into_sorted_vector()`.
+#[derive(Clone)]
+pub struct StableSet<T> {
+ base: FxHashSet<T>,
+}
+
+impl<T> Default for StableSet<T>
+where
+ T: Eq + Hash,
+{
+ fn default() -> StableSet<T> {
+ StableSet::new()
+ }
+}
+
+impl<T> fmt::Debug for StableSet<T>
+where
+ T: Eq + Hash + fmt::Debug,
+{
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ write!(f, "{:?}", self.base)
+ }
+}
+
+impl<T> PartialEq<StableSet<T>> for StableSet<T>
+where
+ T: Eq + Hash,
+{
+ fn eq(&self, other: &StableSet<T>) -> bool {
+ self.base == other.base
+ }
+}
+
+impl<T> Eq for StableSet<T> where T: Eq + Hash {}
+
+impl<T: Hash + Eq> StableSet<T> {
+ pub fn new() -> StableSet<T> {
+ StableSet { base: FxHashSet::default() }
+ }
+
+ pub fn into_sorted_vector(self) -> Vec<T>
+ where
+ T: Ord,
+ {
+ let mut vector = self.base.into_iter().collect::<Vec<_>>();
+ vector.sort_unstable();
+ vector
+ }
+
+ pub fn get<Q: ?Sized>(&self, value: &Q) -> Option<&T>
+ where
+ T: Borrow<Q>,
+ Q: Hash + Eq,
+ {
+ self.base.get(value)
+ }
+
+ pub fn insert(&mut self, value: T) -> bool {
+ self.base.insert(value)
+ }
+
+ pub fn remove<Q: ?Sized>(&mut self, value: &Q) -> bool
+ where
+ T: Borrow<Q>,
+ Q: Hash + Eq,
+ {
+ self.base.remove(value)
+ }
+}