lib/conceptql/operators/union.rb in conceptql-0.2.0 vs lib/conceptql/operators/union.rb in conceptql-0.3.0

@@ -1,19 +1,56 @@
 require_relative 'pass_thru'
 
 module ConceptQL
   module Operators
     class Union < PassThru
+      register __FILE__
+
       desc 'Pools sets of incoming results into a single large set of results.'
       allows_many_upstreams
-      category 'Set Logic'
+      category "Combine Streams"
+      default_query_columns
+      validate_at_least_one_upstream
+      validate_no_arguments
 
       def query(db)
-        values.map do |expression|
+        upstreams.map do |expression|
           expression.evaluate(db).from_self
         end.inject do |q, query|
           q.union(query, all: true)
         end
+      end
+
+      def flattened
+        exprs = []
+        upstreams.each do |x|
+          if x.is_a?(Union)
+            exprs.concat x.flattened.upstreams
+          else
+            exprs << x
+          end
+        end
+        dup_values(exprs)
+      end
+
+      def optimized
+        first, *rest = flattened.upstreams
+        exprs = [first]
+
+        rest.each do |expression|
+          add = true
+          exprs.length.times do |i|
+            exp = exprs[i]
+            if exprs[i].unionable?(expression)
+              exprs[i] = exp.union(expression, all: true)
+              add = false
+              break
+            end
+          end
+          exprs << expression if add
+        end
+
+        dup_values(exprs.map{|x| x.is_a?(Operator) ? x.optimized : x})
       end
     end
   end
 end