mark structures with their fixity

src/prolog/tabled_rc.rs

@@ -1,19 +1,27 @@
 use std::cell::RefCell;
 use std::collections::HashSet;
-use std::hash::Hash;
-use std::ops::Deref;
+use std::fmt;
+use std::hash::{Hash, Hasher};
+use std::ops::{Deref, DerefMut};
 use std::rc::Rc;
 
 pub type TabledData<T> = HashSet<Rc<T>>;
     
-#[derive(Clone, PartialEq, Eq, Hash)]
+#[derive(Clone, PartialEq, Eq)]
 pub struct TabledRc<T: Hash + Eq> {
     atom: Rc<T>,
     table: Rc<RefCell<TabledData<T>>>
 }
 
+impl<T: Hash + Eq> Hash for TabledRc<T> {
+    fn hash<H: Hasher>(&self, state: &mut H)
+    {
+        self.atom.hash(state)        
+    }
+}
+
 impl<T: Hash + Eq> TabledRc<T> {
-    pub fn new(atom: T, table: Rc<RefCell<TabledData<T>>>) -> Self {
+    pub fn new(atom: T, table: Rc<RefCell<TabledData<T>>>) -> Self {        
         TabledRc { atom: Rc::new(atom), table }
     }
 }
@@ -21,8 +29,8 @@ impl<T: Hash + Eq> TabledRc<T> {
 impl<T: Hash + Eq> Drop for TabledRc<T> {
     fn drop(&mut self) {
         if Rc::strong_count(&self.atom) == 2 {
-            let table = *self.table.borrow_mut();
-            table.remove(&self.atom);
+            let mut table = self.table.borrow_mut();
+            table.deref_mut().remove(&self.atom);
         }
     }
 }
@@ -34,3 +42,9 @@ impl<T: Hash + Eq> Deref for TabledRc<T> {
         &*self.atom
     }
 }
+
+impl<T: Hash + Eq + fmt::Display> fmt::Display for TabledRc<T> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}", &*self.atom)
+    }
+}