all: add HashMapExt

src/utils/hash_map_ext.rs

@@ -0,0 +1,15 @@
+use std::collections::HashMap;
+
+pub trait HashMapExt {
+    type V;
+
+    fn drain_values(&mut self) -> impl Iterator<Item = Self::V>;
+}
+
+impl<K, V, S> HashMapExt for HashMap<K, V, S> {
+    type V = V;
+
+    fn drain_values(&mut self) -> impl Iterator<Item = Self::V> {
+        self.drain().map(|(_, v)| v)
+    }
+}