push reduction visitors to a reduction base class

this lets our old depth first and dot visitors to work normally

5 files changed, 36 insertions, 20 deletions

diff --git a/lib/arel/visitors/depth_first.rb b/lib/arel/visitors/depth_first.rb
index 458934f854..4d2ecfa5e1 100644
--- a/lib/arel/visitors/depth_first.rb
+++ b/lib/arel/visitors/depth_first.rb
@@ -5,22 +5,11 @@ module Arel
         @block = block || Proc.new
       end
 
-      def accept object
-        visit object
-      end
-
       private
 
-      def visit object
-        send dispatch[object.class], object
-      rescue NoMethodError => e
-        raise e if respond_to?(dispatch[object.class], true)
-        superklass = object.class.ancestors.find { |klass|
-          respond_to?(dispatch[klass], true)
-        }
-        raise(TypeError, "Cannot visit #{object.class}") unless superklass
-        dispatch[object.class] = dispatch[superklass]
-        retry
+      def visit o
+        super
+        @block.call o
       end
 
       def unary o
diff --git a/lib/arel/visitors/dot.rb b/lib/arel/visitors/dot.rb
index 99f4c467d2..ba35223ac9 100644
--- a/lib/arel/visitors/dot.rb
+++ b/lib/arel/visitors/dot.rb
@@ -23,11 +23,12 @@ module Arel
       end
 
       def accept object
-        super
+        visit object
         to_dot
       end
 
       private
+
       def visit_Arel_Nodes_Ordering o
         visit_edge o, "expr"
       end
diff --git a/lib/arel/visitors/reduce.rb b/lib/arel/visitors/reduce.rb
new file mode 100644
index 0000000000..9670cad27c
--- /dev/null
+++ b/lib/arel/visitors/reduce.rb
@@ -0,0 +1,25 @@
+require 'arel/visitors/visitor'
+
+module Arel
+  module Visitors
+    class Reduce < Arel::Visitors::Visitor
+      def accept object, collector
+        visit object, collector
+      end
+
+      private
+
+      def visit object, collector
+        send dispatch[object.class], object, collector
+      rescue NoMethodError => e
+        raise e if respond_to?(dispatch[object.class], true)
+        superklass = object.class.ancestors.find { |klass|
+          respond_to?(dispatch[klass], true)
+        }
+        raise(TypeError, "Cannot visit #{object.class}") unless superklass
+        dispatch[object.class] = dispatch[superklass]
+        retry
+      end
+    end
+  end
+end
diff --git a/lib/arel/visitors/to_sql.rb b/lib/arel/visitors/to_sql.rb
index f8b8a9a07c..0dbec61212 100644
--- a/lib/arel/visitors/to_sql.rb
+++ b/lib/arel/visitors/to_sql.rb
@@ -1,9 +1,10 @@
 require 'bigdecimal'
 require 'date'
+require 'arel/visitors/reduce'
 
 module Arel
   module Visitors
-    class ToSql < Arel::Visitors::Visitor
+    class ToSql < Arel::Visitors::Reduce
       ##
       # This is some roflscale crazy stuff.  I'm roflscaling this because
       # building SQL queries is a hotspot.  I will explain the roflscale so that
diff --git a/lib/arel/visitors/visitor.rb b/lib/arel/visitors/visitor.rb
index 2d4b472ea3..0730c15794 100644
--- a/lib/arel/visitors/visitor.rb
+++ b/lib/arel/visitors/visitor.rb
@@ -1,8 +1,8 @@
 module Arel
   module Visitors
     class Visitor
-      def accept object, collector
-        visit object, collector
+      def accept object
+        visit object
       end
 
       private
@@ -18,8 +18,8 @@ module Arel
         DISPATCH[self.class]
       end
 
-      def visit object, collector
-        send dispatch[object.class], object, collector
+      def visit object
+        send dispatch[object.class], object
       rescue NoMethodError => e
         raise e if respond_to?(dispatch[object.class], true)
         superklass = object.class.ancestors.find { |klass|