to_sql visitor started

4 files changed, 46 insertions, 0 deletions

diff --git a/lib/arel.rb b/lib/arel.rb
index 4584584c35..ea9a462d1f 100644
--- a/lib/arel.rb
+++ b/lib/arel.rb
@@ -2,6 +2,7 @@ require 'arel/version'
 require 'arel/table'
 require 'arel/attributes'
 require 'arel/nodes'
+require 'arel/visitors/to_sql'
 
 # below is deprecated
 require 'arel/sql/engine'
diff --git a/lib/arel/nodes/equality.rb b/lib/arel/nodes/equality.rb
index 11383b1d89..d778380054 100644
--- a/lib/arel/nodes/equality.rb
+++ b/lib/arel/nodes/equality.rb
@@ -7,6 +7,11 @@ module Arel
         @left  = left
         @right = right
       end
+
+      def to_sql
+        viz = Visitors::ToSql.new left.relation.engine
+        viz.accept self
+      end
     end
   end
 end
diff --git a/lib/arel/table.rb b/lib/arel/table.rb
index 78b3ea9933..0ab39f134d 100644
--- a/lib/arel/table.rb
+++ b/lib/arel/table.rb
@@ -3,6 +3,8 @@ module Arel
     @engine = nil
     class << self; attr_accessor :engine; end
 
+    attr_reader :name, :engine
+
     def initialize name, engine = Table.engine
       @name   = name
       @engine = engine
diff --git a/lib/arel/visitors/to_sql.rb b/lib/arel/visitors/to_sql.rb
new file mode 100644
index 0000000000..ba92ca7ef1
--- /dev/null
+++ b/lib/arel/visitors/to_sql.rb
@@ -0,0 +1,38 @@
+module Arel
+  module Visitors
+    class ToSql
+      def initialize engine
+        @engine     = engine
+        @connection = nil
+      end
+
+      def accept object
+        @connection = @engine.connection
+        visit object
+      end
+
+      private
+      def visit_Arel_Nodes_Equality o
+        "#{visit o.left} = #{visit o.right}"
+      end
+
+      def visit_Arel_Attributes_Integer o
+        "#{quote_table_name o.relation.name}.#{quote_column_name o.name}"
+      end
+
+      def visit_Fixnum o; o end
+
+      def visit object
+        send :"visit_#{object.class.name.gsub('::', '_')}", object
+      end
+
+      def quote_table_name name
+        @connection.quote_table_name name
+      end
+
+      def quote_column_name name
+        @connection.quote_column_name name
+      end
+    end
+  end
+end