adding a join source node

4 files changed, 41 insertions, 18 deletions

diff --git a/lib/arel/nodes/join.rb b/lib/arel/nodes/join.rb
index 07f8c98e85..d3307fe0e0 100644
--- a/lib/arel/nodes/join.rb
+++ b/lib/arel/nodes/join.rb
@@ -1,12 +1,12 @@
 module Arel
   module Nodes
-    class Join < Arel::Nodes::Node
-      attr_accessor :left, :right, :constraint
+    class Join < Arel::Nodes::Binary
 
-      def initialize left, right, constraint
-        @left       = left
-        @right      = right
-        @constraint = constraint
+      alias :single_source :left
+      alias :constraint :right
+
+      def initialize single_source, constraint
+        super
       end
     end
   end
diff --git a/lib/arel/nodes/join_source.rb b/lib/arel/nodes/join_source.rb
new file mode 100644
index 0000000000..7b739c19ad
--- /dev/null
+++ b/lib/arel/nodes/join_source.rb
@@ -0,0 +1,20 @@
+module Arel
+  module Nodes
+    ###
+    # Class that represents a join source
+    #
+    #   http://www.sqlite.org/syntaxdiagrams.html#join-source
+
+    class JoinSource < Arel::Nodes::Binary
+      def initialize single_source, joinop = []
+        super
+      end
+
+      def initialize_copy other
+        super
+        @left  = @left.clone if @left
+        @right = @right.clone if @right
+      end
+    end
+  end
+end
diff --git a/lib/arel/nodes/select_core.rb b/lib/arel/nodes/select_core.rb
index e2293f68a2..bd1930364d 100644
--- a/lib/arel/nodes/select_core.rb
+++ b/lib/arel/nodes/select_core.rb
@@ -1,23 +1,31 @@
 module Arel
   module Nodes
     class SelectCore < Arel::Nodes::Node
-      attr_accessor :from, :projections, :wheres, :groups
-      attr_accessor :having
-
-      alias :froms= :from=
-      alias :froms :from
+      attr_accessor :projections, :wheres, :groups
+      attr_accessor :having, :source
 
       def initialize
-        @from        = nil
+        @source      = JoinSource.new nil
         @projections = []
         @wheres      = []
         @groups      = []
         @having      = nil
       end
 
+      def from
+        @source.left
+      end
+
+      def from= value
+        @source.left = value
+      end
+
+      alias :froms= :from=
+      alias :froms :from
+
       def initialize_copy other
         super
-        @from        = @from.clone if @from
+        @source      = @source.clone if @source
         @projections = @projections.clone
         @wheres      = @wheres.clone
         @group       = @groups.clone
diff --git a/lib/arel/nodes/string_join.rb b/lib/arel/nodes/string_join.rb
index b24e91b6b8..b5420e2dfc 100644
--- a/lib/arel/nodes/string_join.rb
+++ b/lib/arel/nodes/string_join.rb
@@ -1,11 +1,6 @@
 module Arel
   module Nodes
     class StringJoin < Arel::Nodes::Join
-      undef :constraint
-
-      def initialize left, right, on = nil
-        super
-      end
     end
   end
 end