algebra.rb in bmg-0.6.0

- old
+ new

@@ -1,8 +1,21 @@
 module Bmg
   module Algebra
 
+    METHODS = [
+      :allbut,
+      :autowrap,
+      :autosummarize,
+      :constants,
+      :extend,
+      :image,
+      :project,
+      :rename,
+      :restrict,
+      :union
+    ]
+
     def allbut(butlist = [])
       _allbut self.type.allbut(butlist), butlist
     end
 
     def _allbut(type, butlist)
@@ -80,11 +93,15 @@
       else
         type = self.type.restrict(predicate)
         if predicate.contradiction?
           Relation.empty(type)
         else
-          _restrict type, predicate
+          begin
+            _restrict type, predicate
+          rescue Predicate::NotSupportedError
+            Operator::Restrict.new(type, self, predicate)
+          end
         end
       end
     end
 
     def _restrict(type, predicate)
@@ -98,8 +115,17 @@
 
     def _union(type, other, options)
       Operator::Union.new(type, [self, other], options)
     end
     protected :_union
+
+    def spied(spy)
+      return self if spy.nil?
+      Relation::Spied.new(self, spy)
+    end
+
+    def unspied
+      self
+    end
 
   end # module Algebra
 end # module Bmg