Fixed ownership issues in name resolver

src/utils/cache.rs

@@ -1,23 +1,32 @@
-use std::{collections::HashMap, hash::Hash};
+use std::collections::HashMap;
+use std::hash::Hash;
 
 /// Cache the return values of an effectless closure in a hashmap
 /// Inspired by the closure_cacher crate.
-pub struct Cache<I, O, F> where F: FnMut(I) -> O {
+pub struct Cache<I, O, F> {
     store: HashMap<I, O>,
     closure: F
 }
 
-impl<I, O, F> Cache<I, O, F>
-where
-    F: FnMut(I) -> O,
-    I: Eq + Hash + Copy
+impl<I, O, F> Cache<I, O, F> where 
+    I: Eq + Hash,
+    F: FnMut(I) -> O
 {
-    pub fn new(closure: F) -> Self { Self { store: HashMap::new(), closure } }
-    pub fn get(&mut self, i: I) -> &O {
-        // I copied it because I might need `drop` and I prefer `I` to be unconstrained. 
+    pub fn new(closure: F) -> Self {
+        Self { store: HashMap::new(), closure }
+    }
+    pub fn by_copy(&mut self, i: I) -> &O where I: Copy {
         let closure = &mut self.closure;
         self.store.entry(i).or_insert_with(|| closure(i))
     }
+    pub fn by_clone(&mut self, i: I) -> &O where I: Clone {
+        let closure = &mut self.closure;
+        // Make sure we only clone if necessary
+        self.store.entry(i).or_insert_with_key(|k| closure(k.clone()))
+    }
+    pub fn known(&self, i: &I) -> Option<&O> {
+        self.store.get(i)
+    }
     /// Forget the output for the given input
     pub fn drop(&mut self, i: &I) -> bool {
         self.store.remove(i).is_some()