Small improvements to Earley

examples/python3.g

@@ -116,11 +116,12 @@ AWAIT: "await"
           | atom_expr "." NAME               -> getattr
           | atom
 
-?atom: "(" [yield_expr|testlist_comp] ")"
-     | "[" [testlist_comp] "]"
-     | "{" [dictorsetmaker] "}"
+?atom: "(" [yield_expr|testlist_comp] ")" -> tuple
+     | "[" [testlist_comp] "]"  -> list
+     | "{" [dictorsetmaker] "}" -> dict
      | NAME -> var
-     | number | string+ | "..."
+     | number | string+
+     | "..." -> ellipsis
      | "None"    -> const_none
      | "True"    -> const_true
      | "False"   -> const_false

lark/parsers/earley.py

@@ -107,7 +107,7 @@ class Column:
                         new_tree.rule = old_tree.rule
                         old_tree.set('_ambig', [new_tree])
                     if item.tree.children[0] is old_tree:   # XXX a little hacky!
-                        raise ParseError("Infinite recursion in grammar!")
+                        raise ParseError("Infinite recursion in grammar! (Rule %s)" % item.rule)
                     old_tree.children.append(item.tree)
                 else:
                     self.completed[item] = item
@@ -228,6 +228,12 @@ def _compare_drv(tree1, tree2):
     if not (isinstance(tree1, Tree) and isinstance(tree2, Tree)):
         return compare(tree1, tree2)
 
+    try:
+        rule1, rule2 = tree1.rule, tree2.rule
+    except AttributeError:
+        # Probably trees that don't take part in this parse (better way to distinguish?)
+        return compare(tree1, tree2)
+
     c = _compare_rules(tree1.rule, tree2.rule)
     if c:
         return c