1 files changed, 139 insertions, 0 deletions
diff --git a/third_party/rust/fallible_collections/src/hashmap.rs b/third_party/rust/fallible_collections/src/hashmap.rs
new file mode 100644
index 0000000000..b55361e7a7
--- /dev/null
+++ b/third_party/rust/fallible_collections/src/hashmap.rs
@@ -0,0 +1,139 @@
+//! Implement Fallible HashMap
+use super::TryClone;
+use crate::TryReserveError;
+use core::borrow::Borrow;
+use core::default::Default;
+use core::fmt::Debug;
+use core::hash::Hash;
+
+#[cfg(not(all(feature = "std", feature = "rust_1_57")))]
+type HashMap<K, V> = hashbrown::hash_map::HashMap<K, V>;
+
+#[cfg(all(feature = "std", feature = "rust_1_57"))]
+type HashMap<K, V> = std::collections::HashMap<K, V>;
+
+#[cfg(not(all(feature = "std", feature = "rust_1_57")))]
+use hashbrown::hash_map::{Iter, IntoIter};
+
+#[cfg(all(feature = "std", feature = "rust_1_57"))]
+use std::collections::hash_map::{Iter, IntoIter};
+
+pub struct TryHashMap<K, V> {
+    inner: HashMap<K, V>,
+}
+
+impl<K, V> Default for TryHashMap<K, V> {
+    #[inline(always)]
+    fn default() -> Self {
+        Self {
+            inner: Default::default(),
+        }
+    }
+}
+
+impl<K: Debug, V: Debug> Debug for TryHashMap<K, V> {
+    #[inline]
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        self.inner.fmt(f)
+    }
+}
+
+impl<K, V> TryHashMap<K, V>
+where
+    K: Eq + Hash,
+{
+    #[inline]
+    pub fn with_capacity(capacity: usize) -> Result<Self, TryReserveError> {
+        let mut map = Self {
+            inner: HashMap::new(),
+        };
+        map.reserve(capacity)?;
+        Ok(map)
+    }
+
+    #[inline(always)]
+    pub fn get<Q: ?Sized>(&self, k: &Q) -> Option<&V>
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq,
+    {
+        self.inner.get(k)
+    }
+
+    #[inline]
+    pub fn insert(&mut self, k: K, v: V) -> Result<Option<V>, TryReserveError> {
+        self.reserve(if self.inner.capacity() == 0 { 4 } else { 1 })?;
+        Ok(self.inner.insert(k, v))
+    }
+
+    #[inline(always)]
+    pub fn iter(&self) -> Iter<'_, K, V> {
+        self.inner.iter()
+    }
+
+    #[inline(always)]
+    pub fn len(&self) -> usize {
+        self.inner.len()
+    }
+
+    #[inline(always)]
+    pub fn remove<Q: ?Sized>(&mut self, k: &Q) -> Option<V>
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq,
+    {
+        self.inner.remove(k)
+    }
+
+    #[inline(always)]
+    fn reserve(&mut self, additional: usize) -> Result<(), TryReserveError> {
+        #[cfg(not(all(feature = "std", feature = "rust_1_57")))]
+        {
+            self.inner.try_reserve(additional)
+        }
+
+        #[cfg(all(feature = "std", feature = "rust_1_57"))]
+        {
+            self.inner.try_reserve(additional).map_err(|_| {
+                crate::make_try_reserve_error(self.len(), additional,
+                    core::mem::size_of::<K>() + core::mem::size_of::<V>(),
+                    core::mem::align_of::<K>().max(core::mem::align_of::<V>()),
+                )
+            })
+        }
+    }
+}
+
+impl<K, V> IntoIterator for TryHashMap<K, V> {
+    type Item = (K, V);
+    type IntoIter = IntoIter<K, V>;
+
+    #[inline(always)]
+    fn into_iter(self) -> Self::IntoIter {
+        self.inner.into_iter()
+    }
+}
+
+impl<K, V> TryClone for TryHashMap<K, V>
+where
+    K: Eq + Hash + TryClone,
+    V: TryClone,
+{
+    fn try_clone(&self) -> Result<Self, TryReserveError> {
+        let mut clone = Self::with_capacity(self.inner.len())?;
+
+        for (key, value) in self.inner.iter() {
+            clone.insert(key.try_clone()?, value.try_clone()?)?;
+        }
+
+        Ok(clone)
+    }
+}
+
+#[test]
+fn tryhashmap_oom() {
+    match TryHashMap::<char, char>::default().reserve(core::usize::MAX) {
+        Ok(_) => panic!("it should be OOM"),
+        _ => (),
+    }
+}