mv compiler to compiler/

compiler/rustc_data_structures/src/stable_set.rs

@@ -0,0 +1,77 @@
+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)
+    }
+}