6 files changed, 59 insertions, 21 deletions
diff --git a/lib/arel/collectors/plain_string.rb b/lib/arel/collectors/plain_string.rb
new file mode 100644
index 0000000000..2505bc376e
--- /dev/null
+++ b/lib/arel/collectors/plain_string.rb
@@ -0,0 +1,18 @@
+module Arel
+  module Collectors
+    class PlainString
+      def initialize
+        @str = ''
+      end
+
+      def value
+        @str
+      end
+
+      def << str
+        @str << str
+        self
+      end
+    end
+  end
+end
diff --git a/lib/arel/collectors/sql_string.rb b/lib/arel/collectors/sql_string.rb
index 45001bb507..8ca89ca7bd 100644
--- a/lib/arel/collectors/sql_string.rb
+++ b/lib/arel/collectors/sql_string.rb
@@ -1,21 +1,10 @@
 # encoding: utf-8
 
+require 'arel/collectors/plain_string'
+
 module Arel
   module Collectors
-    class SQLString
-      def initialize
-        @str = ''
-      end
-
-      def value
-        @str
-      end
-
-      def << str
-        @str << str
-        self
-      end
-
+    class SQLString < PlainString
       def add_bind bind
         self << bind.to_s
         self
diff --git a/lib/arel/nodes/window.rb b/lib/arel/nodes/window.rb
index 60259e8c05..fee8eeff7a 100644
--- a/lib/arel/nodes/window.rb
+++ b/lib/arel/nodes/window.rb
@@ -1,10 +1,12 @@
 module Arel
   module Nodes
     class Window < Arel::Nodes::Node
-      attr_accessor :orders, :framing
+      attr_accessor :orders, :framing, :partitions
 
       def initialize
         @orders = []
+        @partitions = []
+        @framing = nil
       end
 
       def order *expr
@@ -15,16 +17,32 @@ module Arel
         self
       end
 
+      def partition *expr
+        # FIXME: We SHOULD NOT be converting these to SqlLiteral automatically
+        @partitions.concat expr.map { |x|
+          String === x || Symbol === x ? Nodes::SqlLiteral.new(x.to_s) : x
+        }
+        self
+      end
+
       def frame(expr)
         @framing = expr
       end
 
       def rows(expr = nil)
-        frame(Rows.new(expr))
+        if @framing
+          Rows.new(expr)
+        else
+          frame(Rows.new(expr))
+        end
       end
 
       def range(expr = nil)
-        frame(Range.new(expr))
+        if @framing
+          Range.new(expr)
+        else
+          frame(Range.new(expr))
+        end
       end
 
       def initialize_copy other
@@ -39,7 +57,8 @@ module Arel
       def eql? other
         self.class == other.class &&
           self.orders == other.orders &&
-          self.framing == other.framing
+          self.framing == other.framing &&
+          self.partitions == other.partitions
       end
       alias :== :eql?
     end
diff --git a/lib/arel/tree_manager.rb b/lib/arel/tree_manager.rb
index 87887800d0..8bff97af78 100644
--- a/lib/arel/tree_manager.rb
+++ b/lib/arel/tree_manager.rb
@@ -15,7 +15,9 @@ module Arel
     end
 
     def to_dot
-      Visitors::Dot.new.accept @ast
+      collector = Arel::Collectors::PlainString.new
+      collector = Visitors::Dot.new.accept @ast, collector
+      collector.value
     end
 
     def visitor
diff --git a/lib/arel/visitors/dot.rb b/lib/arel/visitors/dot.rb
index ba35223ac9..f0cefeabd7 100644
--- a/lib/arel/visitors/dot.rb
+++ b/lib/arel/visitors/dot.rb
@@ -22,9 +22,9 @@ module Arel
         @seen       = {}
       end
 
-      def accept object
+      def accept object, collector
         visit object
-        to_dot
+        collector << to_dot
       end
 
       private
@@ -82,12 +82,14 @@ module Arel
       alias :visit_Arel_Nodes_Range             :unary
 
       def window o
+        visit_edge o, "partitions"
         visit_edge o, "orders"
         visit_edge o, "framing"
       end
       alias :visit_Arel_Nodes_Window            :window
 
       def named_window o
+        visit_edge o, "partitions"
         visit_edge o, "orders"
         visit_edge o, "framing"
         visit_edge o, "name"
diff --git a/lib/arel/visitors/to_sql.rb b/lib/arel/visitors/to_sql.rb
index 7f74ebb402..8c63070084 100644
--- a/lib/arel/visitors/to_sql.rb
+++ b/lib/arel/visitors/to_sql.rb
@@ -336,12 +336,20 @@ module Arel
 
       def visit_Arel_Nodes_Window o, collector
         collector << "("
+
+        if o.partitions.any?
+          collector << "PARTITION BY "
+          collector = inject_join o.partitions, collector, ", "
+        end
+
         if o.orders.any?
+          collector << ' ' if o.partitions.any?
           collector << "ORDER BY "
           collector = inject_join o.orders, collector, ", "
         end
 
         if o.framing
+          collector << ' ' if o.partitions.any? or o.orders.any?
           collector = visit o.framing, collector
         end