checkpoint in reconstruction

src/util/scoped_map.rs

@@ -1,4 +1,6 @@
-use std::{borrow::Borrow, collections::HashMap, hash::Hash};
+use std::borrow::Borrow;
+use std::collections::HashMap;
+use std::hash::Hash;
 
 /// A version of [`std::collections::HashMap`] with a built-in notion of scope.
 #[derive(Clone)]
@@ -105,4 +107,28 @@ impl<K: Eq + Hash + PartialEq, V> ScopedMap<K, V> {
 
         ScopedMap { scopes }
     }
+
+    /// Returns true if this map is completely empty, at every level of
+    /// scope.
+    pub fn is_empty(&self) -> bool {
+        self.scopes.iter().all(|x| x.is_empty())
+    }
+}
+
+impl<K: Clone + Eq + Hash, V: Clone> ScopedMap<K, V> {
+    /// Returns the set of all variables bound at this time, with shadowed
+    /// variables hidden.
+    pub fn bindings(&self) -> HashMap<K, V> {
+        let mut result = HashMap::new();
+
+        for scope in self.scopes.iter().rev() {
+            for (key, value) in scope.iter() {
+                if !result.contains_key(key) {
+                    result.insert(key.clone(), value.clone());
+                }
+            }
+        }
+
+        result
+    }
 }