removed function_sql in favor of polymorphism

Conflicts:

	lib/arel/algebra/primitives/attribute.rb
	lib/arel/algebra/primitives/expression.rb
	spec/arel/unit/primitives/expression_spec.rb

2 files changed, 18 insertions, 10 deletions

diff --git a/lib/arel/algebra/primitives/attribute.rb b/lib/arel/algebra/primitives/attribute.rb
index 5e216770e4..943c5b030e 100644
--- a/lib/arel/algebra/primitives/attribute.rb
+++ b/lib/arel/algebra/primitives/attribute.rb
@@ -109,23 +109,23 @@ module Arel
 
     module Expressions
       def count(distinct = false)
-        distinct ?  Expression.new(self, "DISTINCT").count :  Expression.new(self, "COUNT")
+        distinct ?  Distinct.new(self).count :  Count.new(self)
       end
 
       def sum
-        Expression.new(self, "SUM")
+        Sum.new(self)
       end
 
       def maximum
-        Expression.new(self, "MAX")
+        Maximum.new(self)
       end
 
       def minimum
-        Expression.new(self, "MIN")
+        Minimum.new(self)
       end
 
       def average
-        Expression.new(self, "AVG")
+        Average.new(self)
       end
     end
     include Expressions
diff --git a/lib/arel/algebra/primitives/expression.rb b/lib/arel/algebra/primitives/expression.rb
index b67a5e1f8e..989397720c 100644
--- a/lib/arel/algebra/primitives/expression.rb
+++ b/lib/arel/algebra/primitives/expression.rb
@@ -1,12 +1,12 @@
 module Arel
   class Expression < Attribute
-    attributes :attribute, :function_sql, :alias, :ancestor
+    attributes :attribute, :alias, :ancestor
     deriving :==
     delegate :relation, :to => :attribute
     alias_method :name, :alias
 
-    def initialize(attribute, function_sql, aliaz = nil, ancestor = nil)
-      @attribute, @function_sql, @alias, @ancestor = attribute, function_sql, aliaz, ancestor
+    def initialize(attribute, aliaz = nil, ancestor = nil)
+      @attribute, @alias, @ancestor = attribute, aliaz, ancestor
     end
 
     def aggregation?
@@ -15,11 +15,11 @@ module Arel
 
     module Transformations
       def as(aliaz)
-        Expression.new(attribute, function_sql, aliaz, self)
+        self.class.new(attribute, aliaz, self)
       end
 
       def bind(new_relation)
-        new_relation == relation ? self : Expression.new(attribute.bind(new_relation), function_sql, @alias, self)
+        new_relation == relation ? self : self.class.new(attribute.bind(new_relation), @alias, self)
       end
 
       def to_attribute
@@ -28,4 +28,12 @@ module Arel
     end
     include Transformations
   end
+
+  class Count    < Expression; end
+  class Distinct < Expression; end
+  class Sum      < Expression; end
+  class Maximum  < Expression; end
+  class Minimum  < Expression; end
+  class Average  < Expression; end
 end
+