1 files changed, 63 insertions, 0 deletions
diff --git a/activerecord/lib/arel/nodes/select_core.rb b/activerecord/lib/arel/nodes/select_core.rb
new file mode 100644
index 0000000000..73461ff683
--- /dev/null
+++ b/activerecord/lib/arel/nodes/select_core.rb
@@ -0,0 +1,63 @@
+# frozen_string_literal: true
+
+module Arel # :nodoc: all
+  module Nodes
+    class SelectCore < Arel::Nodes::Node
+      attr_accessor :projections, :wheres, :groups, :windows
+      attr_accessor :havings, :source, :set_quantifier
+
+      def initialize
+        super()
+        @source         = JoinSource.new nil
+
+        # https://ronsavage.github.io/SQL/sql-92.bnf.html#set%20quantifier
+        @set_quantifier = nil
+        @projections    = []
+        @wheres         = []
+        @groups         = []
+        @havings        = []
+        @windows        = []
+      end
+
+      def from
+        @source.left
+      end
+
+      def from=(value)
+        @source.left = value
+      end
+
+      alias :froms= :from=
+      alias :froms :from
+
+      def initialize_copy(other)
+        super
+        @source      = @source.clone if @source
+        @projections = @projections.clone
+        @wheres      = @wheres.clone
+        @groups      = @groups.clone
+        @havings     = @havings.clone
+        @windows     = @windows.clone
+      end
+
+      def hash
+        [
+          @source, @set_quantifier, @projections,
+          @wheres, @groups, @havings, @windows
+        ].hash
+      end
+
+      def eql?(other)
+        self.class == other.class &&
+          self.source == other.source &&
+          self.set_quantifier == other.set_quantifier &&
+          self.projections == other.projections &&
+          self.wheres == other.wheres &&
+          self.groups == other.groups &&
+          self.havings == other.havings &&
+          self.windows == other.windows
+      end
+      alias :== :eql?
+    end
+  end
+end