split off and document GameVars::normalize_varname

src/var.rs

@@ -237,7 +237,19 @@ impl GameVars {
         self.db.insert(key.to_lowercase(), value);
     }
 
-    pub fn set_in_scope(&mut self, fallback_scope: &str, key: &str, value: String) {
+    // This method ensures that the variable name contains a scope separator,
+    // and if a scope is missing, it prefixes the fallback scope.
+    //
+    // Some examples, assuming fallback_scope="Clippy", SCOPE_SEPARATOR="$":
+    //
+    // "" -> "clippy$"
+    // "foo" -> "clippy$foo"
+    // "FOO" -> "clippy$foo"
+    // "$foo" -> "clippy$foo"
+    // "$$foo" -> "$$foo"
+    // "PizzaClippy$foo" -> "pizzaclippy$foo" (unchanged)
+    // "$foo$foo$foo$foo" -> "$foo$foo$foo$foo" (unchanged)
+    pub fn normalize_varname(fallback_scope: &str, key: &str) -> String {
         let parts: Vec<&str> = key.split(SCOPE_SEPARATOR).collect();
         let key: String = if parts.len() == 1 {
             // we got a key like "foo", turn it into "<scope>$foo"
@@ -257,11 +269,14 @@ impl GameVars {
                 key.to_string()
             }
         } else {
-            // we got an empty string. this is bad, but handle gracefully by prefixing scope
+            // we got an empty string. this is bad, but handle gracefully
             fallback_scope.to_string() + SCOPE_SEPARATOR
         };
+        return key.to_lowercase();
+    }
 
-        let key = key.to_lowercase();
+    pub fn set_in_scope(&mut self, fallback_scope: &str, key: &str, value: String) {
+        let key = Self::normalize_varname(fallback_scope, key);
         self.db.insert(key, value);
     }
 }