major refactor.

src/prolog/indexing.rs

@@ -1,5 +1,4 @@
 use prolog::ast::*;
-use prolog::tabled_rc::*;
 
 use std::collections::{HashMap, VecDeque};
 use std::hash::Hash;
@@ -12,7 +11,7 @@ enum IntIndex {
 pub struct CodeOffsets {
     pub constants:  HashMap<Constant, ThirdLevelIndex>,
     pub lists: ThirdLevelIndex,
-    pub structures: HashMap<(TabledRc<Atom>, usize), ThirdLevelIndex>
+    pub structures: HashMap<(ClauseName, usize), ThirdLevelIndex>
 }
 
 impl CodeOffsets {
@@ -145,7 +144,7 @@ impl CodeOffsets {
         }
     }
 
-    fn switch_on_structure(str_ind: HashMap<(TabledRc<Atom>, usize), ThirdLevelIndex>,
+    fn switch_on_structure(str_ind: HashMap<(ClauseName, usize), ThirdLevelIndex>,
                            prelude: &mut CodeDeque)
                            -> IntIndex
     {