Merge remote branch 'stiff/master' into omg

* stiff/master:
  implemented support for math operations in numeric attributes

6 files changed, 61 insertions, 3 deletions

diff --git a/lib/arel.rb b/lib/arel.rb
index 32fc8d9bc0..de429f532e 100644
--- a/lib/arel.rb
+++ b/lib/arel.rb
@@ -3,6 +3,7 @@ require 'arel/factory_methods'
 
 require 'arel/expressions'
 require 'arel/predications'
+require 'arel/math'
 require 'arel/table'
 require 'arel/attributes'
 require 'arel/compatibility/wheres'
diff --git a/lib/arel/attributes/attribute.rb b/lib/arel/attributes/attribute.rb
index 9a42e5a4da..bd3f4b58f1 100644
--- a/lib/arel/attributes/attribute.rb
+++ b/lib/arel/attributes/attribute.rb
@@ -5,12 +5,16 @@ module Arel
       include Arel::Predications
     end
 
+    class NumericAttribute < Attribute
+      include Arel::Math
+    end
+
     class String    < Attribute; end
     class Time      < Attribute; end
     class Boolean   < Attribute; end
-    class Decimal   < Attribute; end
-    class Float     < Attribute; end
-    class Integer   < Attribute; end
+    class Decimal   < NumericAttribute; end
+    class Float     < NumericAttribute; end
+    class Integer   < NumericAttribute; end
     class Undefined < Attribute; end
   end
 
diff --git a/lib/arel/math.rb b/lib/arel/math.rb
new file mode 100644
index 0000000000..551b1f1010
--- /dev/null
+++ b/lib/arel/math.rb
@@ -0,0 +1,21 @@
+module Arel
+  module Math
+
+    def *(other)
+      Arel::Nodes::Multiplication.new(self, other)
+    end
+
+    def +(other)
+      Arel::Nodes::Addition.new(self, other)
+    end
+
+    def -(other)
+      Arel::Nodes::Subtraction.new(self, other)
+    end
+
+    def /(other)
+      Arel::Nodes::Division.new(self, other)
+    end
+  
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/nodes.rb b/lib/arel/nodes.rb
index 442b313593..4b97e28668 100644
--- a/lib/arel/nodes.rb
+++ b/lib/arel/nodes.rb
@@ -18,6 +18,7 @@ require 'arel/nodes/join_source'
 require 'arel/nodes/ordering'
 require 'arel/nodes/delete_statement'
 require 'arel/nodes/table_alias'
+require 'arel/nodes/math_operation'
 
 # nary
 require 'arel/nodes/and'
diff --git a/lib/arel/nodes/math_operation.rb b/lib/arel/nodes/math_operation.rb
new file mode 100644
index 0000000000..d9820f1ece
--- /dev/null
+++ b/lib/arel/nodes/math_operation.rb
@@ -0,0 +1,15 @@
+module Arel
+  module Nodes
+    class MathOperation < Binary
+      include Arel::Expressions
+      include Arel::Predications
+      include Arel::Math
+    end
+
+    class Multiplication < MathOperation; end
+    class Division < MathOperation; end
+    class Addition < MathOperation; end
+    class Subtraction < MathOperation; end
+
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/visitors/to_sql.rb b/lib/arel/visitors/to_sql.rb
index 70e10a5e0f..7eaaff8e13 100644
--- a/lib/arel/visitors/to_sql.rb
+++ b/lib/arel/visitors/to_sql.rb
@@ -373,6 +373,22 @@ key on UpdateManager using UpdateManager#key=
       alias :visit_Time                          :quoted
       alias :visit_TrueClass                     :quoted
 
+      def visit_Arel_Nodes_Multiplication o
+        "#{visit o.left} * #{visit o.right}"
+      end
+
+      def visit_Arel_Nodes_Division o
+        "#{visit o.left} / #{visit o.right}"
+      end
+
+      def visit_Arel_Nodes_Addition o
+        "(#{visit o.left} + #{visit o.right})"
+      end
+
+      def visit_Arel_Nodes_Subtraction o
+        "(#{visit o.left} - #{visit o.right})"
+      end
+
       def visit_Array o
         o.empty? ? 'NULL' : o.map { |x| visit x }.join(', ')
       end