remove Term

src/machine/attributed_variables.rs

@@ -11,8 +11,8 @@ use std::vec::IntoIter;
 pub(super) type Bindings = Vec<(usize, HeapCellValue)>;
 
 #[derive(Debug)]
-pub(super) struct AttrVarInitializer {
-    pub(super) attr_var_queue: Vec<usize>,
+pub(crate) struct AttrVarInitializer {
+    pub(crate) attr_var_queue: Vec<usize>,
     pub(super) bindings: Bindings,
     pub(super) p: usize,
     pub(super) cp: usize,
@@ -131,9 +131,15 @@ impl MachineState {
     pub(super) fn attr_vars_of_term(&mut self, cell: HeapCellValue) -> Vec<HeapCellValue> {
         let mut seen_set = IndexSet::new();
         let mut seen_vars = vec![];
+        let root_loc = if cell.is_ref() {
+            cell.get_value() as usize
+        } else {
+            return vec![];
+        };
 
-        let mut iter =
-            stackful_preorder_iter::<NonListElider>(&mut self.heap, &mut self.stack, cell);
+        let mut iter = stackful_preorder_iter::<NonListElider>(
+            &mut self.heap, &mut self.stack, root_loc, // cell,
+        );
 
         while let Some(value) = iter.next() {
             read_heap_cell!(value,