From eef61ab909b614ce6f2d100cfb50044c063bc24a Mon Sep 17 00:00:00 2001
From: Ernie Miller <ernie@metautonomo.us>
Date: Wed, 29 Sep 2010 20:08:57 -0400
Subject: Support Attribute#asc and Attribute#desc to create orderings

---
 lib/arel/attributes/attribute.rb |  8 ++++++++
 lib/arel/nodes.rb                |  1 +
 lib/arel/nodes/ordering.rb       | 19 +++++++++++++++++++
 lib/arel/visitors/dot.rb         |  5 +++++
 lib/arel/visitors/to_sql.rb      |  4 ++++
 5 files changed, 37 insertions(+)
 create mode 100644 lib/arel/nodes/ordering.rb

(limited to 'lib/arel')

diff --git a/lib/arel/attributes/attribute.rb b/lib/arel/attributes/attribute.rb
index 25ffe717b2..ba18533590 100644
--- a/lib/arel/attributes/attribute.rb
+++ b/lib/arel/attributes/attribute.rb
@@ -151,6 +151,14 @@ module Arel
         grouping_all :lteq, others
       end
 
+      def asc
+        Nodes::Ordering.new self, :asc
+      end
+
+      def desc
+        Nodes::Ordering.new self, :desc
+      end
+
       private
 
       def grouping_any method_id, others
diff --git a/lib/arel/nodes.rb b/lib/arel/nodes.rb
index 0063ed1cd5..47cbd64eb5 100644
--- a/lib/arel/nodes.rb
+++ b/lib/arel/nodes.rb
@@ -15,6 +15,7 @@ require 'arel/nodes/does_not_match'
 
 require 'arel/nodes/in'
 require 'arel/nodes/not_in'
+require 'arel/nodes/ordering'
 require 'arel/nodes/lock'
 require 'arel/nodes/function'
 require 'arel/nodes/count'
diff --git a/lib/arel/nodes/ordering.rb b/lib/arel/nodes/ordering.rb
new file mode 100644
index 0000000000..d395c8631d
--- /dev/null
+++ b/lib/arel/nodes/ordering.rb
@@ -0,0 +1,19 @@
+module Arel
+  module Nodes
+    class Ordering < Arel::Nodes::Node
+      attr_accessor :expr, :direction
+
+      def initialize expression, direction = :asc
+        @expr, @direction = expression, direction
+      end
+
+      def ascending?
+        direction == :asc
+      end
+
+      def descending?
+        direction == :desc
+      end
+    end
+  end
+end
diff --git a/lib/arel/visitors/dot.rb b/lib/arel/visitors/dot.rb
index 655c75aab9..5202c5127e 100644
--- a/lib/arel/visitors/dot.rb
+++ b/lib/arel/visitors/dot.rb
@@ -32,6 +32,11 @@ module Arel
         visit_edge o, "expr"
       end
 
+      def visit_Arel_Nodes_Ordering o
+        visit_edge o, "expr"
+        visit_edge o, "direction"
+      end
+
       def visit_Arel_Nodes_TableAlias o
         visit_edge o, "name"
         visit_edge o, "relation"
diff --git a/lib/arel/visitors/to_sql.rb b/lib/arel/visitors/to_sql.rb
index 405578f604..17779b4037 100644
--- a/lib/arel/visitors/to_sql.rb
+++ b/lib/arel/visitors/to_sql.rb
@@ -107,6 +107,10 @@ module Arel
         "(#{visit o.expr})"
       end
 
+      def visit_Arel_Nodes_Ordering o
+        "#{visit o.expr} #{o.descending? ? 'DESC' : 'ASC'}"
+      end
+
       def visit_Arel_Nodes_Group o
         visit o.expr
       end
-- 
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