Introduce NodeExpression as parent of scalar nodes

SQL is very powerful. Many nodes can be used as a sub expression or
query. grouping all of these possible nodes together

14 files changed, 21 insertions, 25 deletions

diff --git a/lib/arel/nodes.rb b/lib/arel/nodes.rb
index bb8ad6500b..8c6572dd6a 100644
--- a/lib/arel/nodes.rb
+++ b/lib/arel/nodes.rb
@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 # node
 require 'arel/nodes/node'
+require 'arel/nodes/node_expression'
 require 'arel/nodes/select_statement'
 require 'arel/nodes/select_core'
 require 'arel/nodes/insert_statement'
diff --git a/lib/arel/nodes/binary.rb b/lib/arel/nodes/binary.rb
index 3001788774..a86d4e4696 100644
--- a/lib/arel/nodes/binary.rb
+++ b/lib/arel/nodes/binary.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 module Arel
   module Nodes
-    class Binary < Arel::Nodes::Node
+    class Binary < Arel::Nodes::NodeExpression
       attr_accessor :left, :right
 
       def initialize left, right
diff --git a/lib/arel/nodes/case.rb b/lib/arel/nodes/case.rb
index 1edca40001..50ea1e0be2 100644
--- a/lib/arel/nodes/case.rb
+++ b/lib/arel/nodes/case.rb
@@ -2,10 +2,6 @@
 module Arel
   module Nodes
     class Case < Arel::Nodes::Node
-      include Arel::OrderPredications
-      include Arel::Predications
-      include Arel::AliasPredication
-
       attr_accessor :case, :conditions, :default
 
       def initialize expression = nil, default = nil
diff --git a/lib/arel/nodes/casted.rb b/lib/arel/nodes/casted.rb
index 1d7385d01b..f945063dd2 100644
--- a/lib/arel/nodes/casted.rb
+++ b/lib/arel/nodes/casted.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 module Arel
   module Nodes
-    class Casted < Arel::Nodes::Node # :nodoc:
+    class Casted < Arel::Nodes::NodeExpression # :nodoc:
       attr_reader :val, :attribute
       def initialize val, attribute
         @val       = val
diff --git a/lib/arel/nodes/extract.rb b/lib/arel/nodes/extract.rb
index 4e797b6770..fdf3004c6a 100644
--- a/lib/arel/nodes/extract.rb
+++ b/lib/arel/nodes/extract.rb
@@ -2,9 +2,6 @@
 module Arel
   module Nodes
     class Extract < Arel::Nodes::Unary
-      include Arel::AliasPredication
-      include Arel::Predications
-
       attr_accessor :field
 
       def initialize expr, field
diff --git a/lib/arel/nodes/false.rb b/lib/arel/nodes/false.rb
index fb821dd522..58132a2f90 100644
--- a/lib/arel/nodes/false.rb
+++ b/lib/arel/nodes/false.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 module Arel
   module Nodes
-    class False < Arel::Nodes::Node
+    class False < Arel::Nodes::NodeExpression
       def hash
         self.class.hash
       end
diff --git a/lib/arel/nodes/function.rb b/lib/arel/nodes/function.rb
index b2b89ee9ff..b3bf8f3e51 100644
--- a/lib/arel/nodes/function.rb
+++ b/lib/arel/nodes/function.rb
@@ -1,10 +1,8 @@
 # frozen_string_literal: true
 module Arel
   module Nodes
-    class Function < Arel::Nodes::Node
-      include Arel::Predications
+    class Function < Arel::Nodes::NodeExpression
       include Arel::WindowPredications
-      include Arel::OrderPredications
       attr_accessor :expressions, :alias, :distinct
 
       def initialize expr, aliaz = nil
diff --git a/lib/arel/nodes/grouping.rb b/lib/arel/nodes/grouping.rb
index 16911eb3b6..ffe66654ce 100644
--- a/lib/arel/nodes/grouping.rb
+++ b/lib/arel/nodes/grouping.rb
@@ -2,7 +2,6 @@
 module Arel
   module Nodes
     class Grouping < Unary
-      include Arel::Predications
     end
   end
 end
diff --git a/lib/arel/nodes/node_expression.rb b/lib/arel/nodes/node_expression.rb
new file mode 100644
index 0000000000..c4d4c8f428
--- /dev/null
+++ b/lib/arel/nodes/node_expression.rb
@@ -0,0 +1,11 @@
+module Arel
+  module Nodes
+    class NodeExpression < Arel::Nodes::Node
+      include Arel::Expressions
+      include Arel::Predications
+      include Arel::AliasPredication
+      include Arel::OrderPredications
+      include Arel::Math
+    end
+  end
+end
diff --git a/lib/arel/nodes/select_statement.rb b/lib/arel/nodes/select_statement.rb
index 641a08405d..79176d4be5 100644
--- a/lib/arel/nodes/select_statement.rb
+++ b/lib/arel/nodes/select_statement.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 module Arel
   module Nodes
-    class SelectStatement < Arel::Nodes::Node
+    class SelectStatement < Arel::Nodes::NodeExpression
       attr_reader :cores
       attr_accessor :limit, :orders, :lock, :offset, :with
 
diff --git a/lib/arel/nodes/terminal.rb b/lib/arel/nodes/terminal.rb
index 421f039904..3a1cd7f0e1 100644
--- a/lib/arel/nodes/terminal.rb
+++ b/lib/arel/nodes/terminal.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 module Arel
   module Nodes
-    class Distinct < Arel::Nodes::Node
+    class Distinct < Arel::Nodes::NodeExpression
       def hash
         self.class.hash
       end
diff --git a/lib/arel/nodes/true.rb b/lib/arel/nodes/true.rb
index bb9d8c1414..fdb8ed2095 100644
--- a/lib/arel/nodes/true.rb
+++ b/lib/arel/nodes/true.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 module Arel
   module Nodes
-    class True < Arel::Nodes::Node
+    class True < Arel::Nodes::NodeExpression
       def hash
         self.class.hash
       end
diff --git a/lib/arel/nodes/unary.rb b/lib/arel/nodes/unary.rb
index a42744b1d5..5711d91dce 100644
--- a/lib/arel/nodes/unary.rb
+++ b/lib/arel/nodes/unary.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 module Arel
   module Nodes
-    class Unary < Arel::Nodes::Node
+    class Unary < Arel::Nodes::NodeExpression
       attr_accessor :expr
       alias :value :expr
 
diff --git a/lib/arel/nodes/unary_operation.rb b/lib/arel/nodes/unary_operation.rb
index 3c56ef2026..be4e270e76 100644
--- a/lib/arel/nodes/unary_operation.rb
+++ b/lib/arel/nodes/unary_operation.rb
@@ -3,12 +3,6 @@ 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
@@ -23,4 +17,4 @@ module Arel
       end
     end
   end
-end
\ No newline at end of file
+end