* Support for bitwise operations as infix operators. Tests included.

*** Individual commit messages included below ***
* Preliminary support for bitwise operations as infix operators.  Tests to follow.

* Added bitwise xor, shift left and shift right operators

* Fixed the BitwiseOr class so it uses the :| operator instead of :&
* All the methods for the bitwise operators in the Arel::Math module now wrap them up in Arel::Nodes::Grouping so the operation becomes isolated like addition and subtraction
* Preliminary set of tests for the new operators

* Updated README with examples of bitwise operations

* Added a new UnaryOperation class which is a riff on the InfixOperation class
* Added tests for UnaryOperation (inspired by InfixOperation tests)
* Added the bitwise not (~) operator as a UnaryOperation
* Added tests for the bitwise not operator

* Added documentation for the bitwise not operator

* Updated gemspec using `rake arel.gemspec`

2 files changed, 55 insertions, 0 deletions

diff --git a/lib/arel/nodes/infix_operation.rb b/lib/arel/nodes/infix_operation.rb
index a3f04da6fa..55ac715f73 100644
--- a/lib/arel/nodes/infix_operation.rb
+++ b/lib/arel/nodes/infix_operation.rb
@@ -45,5 +45,35 @@ module Arel
         super('||', left, right)
       end
     end
+
+    class BitwiseAnd < InfixOperation
+      def initialize left, right
+        super(:&, left, right)
+      end
+    end
+
+    class BitwiseOr < InfixOperation
+      def initialize left, right
+        super(:|, left, right)
+      end
+    end
+
+    class BitwiseXor < InfixOperation
+      def initialize left, right
+        super(:^, left, right)
+      end
+    end
+
+    class BitwiseShiftLeft < InfixOperation
+      def initialize left, right
+        super(:<<, left, right)
+      end
+    end
+
+    class BitwiseShiftRight < InfixOperation
+      def initialize left, right
+        super(:>>, left, right)
+      end
+    end
   end
 end
diff --git a/lib/arel/nodes/unary_operation.rb b/lib/arel/nodes/unary_operation.rb
new file mode 100644
index 0000000000..1636c01279
--- /dev/null
+++ b/lib/arel/nodes/unary_operation.rb
@@ -0,0 +1,25 @@
+module Arel
+  module Nodes
+
+    class UnaryOperation < Unary
+      include Arel::Expressions
+      include Arel::Predications
+      include Arel::OrderPredications
+      include Arel::AliasPredication
+      include Arel::Math
+
+      attr_reader :operator
+
+      def initialize operator, operand
+        super(operand)
+        @operator = operator
+      end
+    end
+
+    class BitwiseNot < UnaryOperation
+      def initialize operand
+        super(:~, operand)
+      end
+    end
+  end
+end
\ No newline at end of file