From ed6192c55b8e77b60e4203dc30ae056f222a1499 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Wed, 15 Sep 2010 09:26:01 -0700
Subject: [PATCH] adding a grouping node

---
 lib/arel/nodes.rb                |  2 ++
 lib/arel/nodes/binary.rb         | 10 +---------
 lib/arel/nodes/grouping.rb       | 21 +++++++++++++++++++++
 lib/arel/nodes/node.rb           | 20 ++++++++++++++++++++
 lib/arel/visitors/to_sql.rb      |  4 ++++
 spec/arel/nodes/equality_spec.rb |  4 ++--
 spec/arel/nodes/or_spec.rb       |  8 ++++----
 7 files changed, 54 insertions(+), 15 deletions(-)
 create mode 100644 lib/arel/nodes/grouping.rb
 create mode 100644 lib/arel/nodes/node.rb

diff --git a/lib/arel/nodes.rb b/lib/arel/nodes.rb
index 99a34c3b2b..ac4bba57c2 100644
--- a/lib/arel/nodes.rb
+++ b/lib/arel/nodes.rb
@@ -1,3 +1,4 @@
+require 'arel/nodes/node'
 require 'arel/nodes/binary'
 require 'arel/nodes/equality'
 require 'arel/nodes/not_equal'
@@ -29,6 +30,7 @@ require 'arel/nodes/unqualified_column'
 require 'arel/nodes/table_alias'
 require 'arel/nodes/join'
 require 'arel/nodes/group'
+require 'arel/nodes/grouping'
 require 'arel/nodes/inner_join'
 require 'arel/nodes/outer_join'
 require 'arel/nodes/string_join'
diff --git a/lib/arel/nodes/binary.rb b/lib/arel/nodes/binary.rb
index 3cd9583e79..090468adfa 100644
--- a/lib/arel/nodes/binary.rb
+++ b/lib/arel/nodes/binary.rb
@@ -1,6 +1,6 @@
 module Arel
   module Nodes
-    class Binary
+    class Binary < Arel::Nodes::Node
       attr_accessor :left, :right
 
       def initialize left, right
@@ -8,14 +8,6 @@ module Arel
         @right = right
       end
 
-      def or right
-        Nodes::Or.new self, right
-      end
-
-      def and right
-        Nodes::And.new self, right
-      end
-
       # FIXME: this method should go away.  I don't like people calling
       # to_sql on non-head nodes.  This forces us to walk the AST until we
       # can find a node that has a "relation" member.
diff --git a/lib/arel/nodes/grouping.rb b/lib/arel/nodes/grouping.rb
new file mode 100644
index 0000000000..0af1df1f7a
--- /dev/null
+++ b/lib/arel/nodes/grouping.rb
@@ -0,0 +1,21 @@
+module Arel
+  module Nodes
+    class Grouping < Arel::Nodes::Node
+      attr_accessor :expr
+
+      def initialize expression
+        @expr = expression
+      end
+
+      # FIXME: this method should go away.  I don't like people calling
+      # to_sql on non-head nodes.  This forces us to walk the AST until we
+      # can find a node that has a "relation" member.
+      #
+      # Maybe we should just use `Table.engine`?  :'(
+      def to_sql
+        viz = Visitors::ToSql.new Table.engine
+        viz.accept self
+      end
+    end
+  end
+end
diff --git a/lib/arel/nodes/node.rb b/lib/arel/nodes/node.rb
new file mode 100644
index 0000000000..fd5ea410ea
--- /dev/null
+++ b/lib/arel/nodes/node.rb
@@ -0,0 +1,20 @@
+module Arel
+  module Nodes
+    ###
+    # Abstract base class for all AST nodes
+    class Node
+      ###
+      # Factory method to create a Nodes::Grouping node that has an Nodes::Or
+      # node as a child.
+      def or right
+        Nodes::Grouping.new Nodes::Or.new(self, right)
+      end
+
+      ###
+      # Factory method to create an Nodes::And node.
+      def and right
+        Nodes::And.new self, right
+      end
+    end
+  end
+end
diff --git a/lib/arel/visitors/to_sql.rb b/lib/arel/visitors/to_sql.rb
index 46f70d0f7c..5be95565f3 100644
--- a/lib/arel/visitors/to_sql.rb
+++ b/lib/arel/visitors/to_sql.rb
@@ -84,6 +84,10 @@ module Arel
       def visit_Arel_Nodes_Lock o
       end
 
+      def visit_Arel_Nodes_Grouping o
+        "(#{visit o.expr})"
+      end
+
       def visit_Arel_Nodes_Group o
         visit o.expr
       end
diff --git a/spec/arel/nodes/equality_spec.rb b/spec/arel/nodes/equality_spec.rb
index d9edc352f3..81eea4d482 100644
--- a/spec/arel/nodes/equality_spec.rb
+++ b/spec/arel/nodes/equality_spec.rb
@@ -34,8 +34,8 @@ module Arel
           left  = attr.eq(10)
           right = attr.eq(11)
           node  = left.or right
-          check node.left.should == left
-          check node.right.should == right
+          check node.expr.left.should == left
+          check node.expr.right.should == right
         end
       end
 
diff --git a/spec/arel/nodes/or_spec.rb b/spec/arel/nodes/or_spec.rb
index e855b92453..88484ff4f7 100644
--- a/spec/arel/nodes/or_spec.rb
+++ b/spec/arel/nodes/or_spec.rb
@@ -7,12 +7,12 @@ module Arel
           left  = attr.eq(10)
           right = attr.eq(11)
           node  = left.or right
-          check node.left.should == left
-          check node.right.should == right
+          check node.expr.left.should == left
+          check node.expr.right.should == right
 
           oror = node.or(right)
-          check oror.left == node
-          check oror.right == right
+          check oror.expr.left == node
+          check oror.expr.right == right
         end
       end
     end