1 files changed, 107 insertions, 0 deletions
diff --git a/third_party/rust/clap_builder/src/util/flat_set.rs b/third_party/rust/clap_builder/src/util/flat_set.rs
new file mode 100644
index 0000000000..3e0b23dae3
--- /dev/null
+++ b/third_party/rust/clap_builder/src/util/flat_set.rs
@@ -0,0 +1,107 @@
+#![allow(dead_code)]
+
+use std::borrow::Borrow;
+
+/// Flat (Vec) backed set
+///
+/// This preserves insertion order
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub(crate) struct FlatSet<T> {
+    inner: Vec<T>,
+}
+
+impl<T: PartialEq + Eq> FlatSet<T> {
+    pub(crate) fn new() -> Self {
+        Default::default()
+    }
+
+    pub(crate) fn insert(&mut self, value: T) -> bool {
+        for existing in &self.inner {
+            if *existing == value {
+                return false;
+            }
+        }
+        self.inner.push(value);
+        true
+    }
+
+    pub fn contains<Q: ?Sized>(&self, value: &Q) -> bool
+    where
+        T: Borrow<Q>,
+        Q: Eq,
+    {
+        for existing in &self.inner {
+            if existing.borrow() == value {
+                return true;
+            }
+        }
+        false
+    }
+
+    pub fn retain<F>(&mut self, f: F)
+    where
+        F: FnMut(&T) -> bool,
+    {
+        self.inner.retain(f);
+    }
+
+    pub(crate) fn is_empty(&self) -> bool {
+        self.inner.is_empty()
+    }
+
+    pub(crate) fn iter(&self) -> std::slice::Iter<'_, T> {
+        self.inner.iter()
+    }
+
+    pub fn sort_by_key<K, F>(&mut self, f: F)
+    where
+        F: FnMut(&T) -> K,
+        K: Ord,
+    {
+        self.inner.sort_by_key(f);
+    }
+}
+
+impl<T: PartialEq + Eq> Default for FlatSet<T> {
+    fn default() -> Self {
+        Self {
+            inner: Default::default(),
+        }
+    }
+}
+
+impl<T: PartialEq + Eq> IntoIterator for FlatSet<T> {
+    type Item = T;
+    type IntoIter = std::vec::IntoIter<T>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.inner.into_iter()
+    }
+}
+
+impl<'s, T: PartialEq + Eq> IntoIterator for &'s FlatSet<T> {
+    type Item = &'s T;
+    type IntoIter = std::slice::Iter<'s, T>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.inner.iter()
+    }
+}
+
+impl<T: PartialEq + Eq> Extend<T> for FlatSet<T> {
+    fn extend<I: IntoIterator<Item = T>>(&mut self, iter: I) {
+        for value in iter {
+            self.insert(value);
+        }
+    }
+}
+
+impl<T: PartialEq + Eq> FromIterator<T> for FlatSet<T> {
+    fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> Self {
+        let mut set = Self::new();
+        for value in iter {
+            set.insert(value);
+        }
+        set
+    }
+}