refactor: arel fetch_attribute to get the atrribute node from binary

module.

Reason for doing this change is to pull the node specific changes to
module itself and to not infer on the attributes, rather than assign
responsibility to the member functions to do so.

activerecord/lib/arel.rb

@@ -51,11 +51,8 @@ module Arel
     when Arel::Nodes::Between, Arel::Nodes::In, Arel::Nodes::NotIn, Arel::Nodes::Equality,
          Arel::Nodes::NotEqual, Arel::Nodes::LessThan, Arel::Nodes::LessThanOrEqual,
          Arel::Nodes::GreaterThan, Arel::Nodes::GreaterThanOrEqual
-      if value.left.is_a?(Arel::Attributes::Attribute)
-        yield value.left
-      elsif value.right.is_a?(Arel::Attributes::Attribute)
-        yield value.right
-      end
+      attribute_value = value.detect_attribute
+      yield attribute_value if attribute_value
     when Arel::Nodes::Or
       fetch_attribute(value.left, &block) && fetch_attribute(value.right, &block)
     when Arel::Nodes::Grouping

activerecord/lib/arel/nodes/binary.rb

@@ -11,6 +11,14 @@ module Arel # :nodoc: all
         @right = right
       end
 
+      def detect_attribute
+        if self.left.is_a?(Arel::Attributes::Attribute)
+          self.left
+        elsif self.right.is_a?(Arel::Attributes::Attribute)
+          self.right
+        end
+      end
+
       def initialize_copy(other)
         super
         @left  = @left.clone if @left