lib/bmg/operator/constants.rb in bmg-0.4.0 vs lib/bmg/operator/constants.rb in bmg-0.4.1

@@ -34,21 +34,23 @@
       end
 
     protected ### optimization
 
       def _restrict(type, predicate)
+        # bottom_p makes no reference to constants, top_p possibly
+        # does...
         top_p, bottom_p = predicate.and_split(constants.keys)
         if top_p.tautology?
-          # push all situation
+          # push all situation: predicate made no reference to constants
           result = operand
-          result = result.restrict(bottom_p) unless bottom_p.tautology?
+          result = result.restrict(bottom_p)
           result = result.constants(constants)
           result
         elsif (top_p.free_variables - constants.keys).empty?
           # top_p applies to constants only
           if eval = top_p.evaluate(constants)
             result = operand
-            result = result.restrict(bottom_p) unless bottom_p.tautology?
+            result = result.restrict(bottom_p)
             result = result.constants(constants)
             result
           else
             Relation.empty(type)
           end